Acta geographica Slovenica, 61-2, 2021, 41–71
PRECIPITATION VARIABILITY,
TRENDS AND REGIONS IN POLAND:
TEMPORAL AND SPATIAL
DISTRIBUTION IN THE YEARS
1951–2018
Robert Kalbarczyk, Eliza Kalbarczyk
Crowns of Scots pine trees in the clouds.
R O B E R T K A L B A R C Z Y K

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
42
DOI: https://doi.org/10.3986/AGS.8846
UDC: 913:551.435.11:502.13(497.11)
COBISS: 1.01
Robert Kalbarczyk
1
, Eliza Kalbarczyk
2
Precipitation variability, trends and regions in Poland: Temporal and spatial
distribution in the years 1951–2018 
ABSTRACT: The goals of this work were to assess differences in precipitation totals (Pr) in Poland in both
time and space and to distinguish regions based on precipitation variability in the years 1951–2018. To
assess precipitation conditions, the study used statistical and spatial analyses implemented in ArcGIS Desktop
and STATISTICA software. The largest number of significant, positive correlations describing the linear
Pr trend were found for March. The lowest monthly Pr, which represents only approximately 6% of the
multi-year precipitation totals, was recorded in October 1951; the highest monthly Pr, which represents
as much as approximately 355% of the multi-year precipitation totals, was recorded in October 1974. The
study distinguished three precipitation regions of Poland.
KEY WORDS: climate change, precipitation conditions, number of days with precipitation, precipitation
regions, Poland.
Spremenljivost, trendi in območja padavin na Poljskem: časovna in prostorska
porazdelitev med letoma 1951 in 2018
POVZETEK: V članku so proučene razlike v skupni količini padavin na Poljskem v času in prostoru, na
podlagi česar so določena glavna padavinska območja med letoma 1951 in 2018. Padavinske razmere so
ocenjene na podlagi statistične in prostorske analize, opravljene v programskih orodjih ArcGIS Desktop
in STATISTICA. Največ statistično značilnih korelacij, ki nakazujejo linearni trend v skupni količini padavin,
je bilo odkritih za mesec marec. Najmanjša mesečna skupna količina padavin (samo približno 6 % večletnega
mesečnega povprečja) je bila zabeležena oktobra 1951, najvišja (približno 355 % večletnega mesečnega
povprečja) pa oktobra 1974. Določena so tri padavinska območja na Poljskem.
KLJUČNE BESEDE: podnebne spremembe, padavinske razmere, število dni s padavinami, padavinska
območja, Poljska
The paper was submitted for publication on August 3
rd
, 2020.
Uredništvo je prejelo prispevek 3. avgusta 2020.
1
Wrocław University of Environmental and Life Sciences, Institute of Landscape Architecture, Wrocław,
Poland
robert.kalbarczyk@upwr.edu.pl (https://orcid.org/0000-0002-0564-8653)
2
Adam Mickiewicz University in Poznań, Faculty of Human Geography and Planning, Poznań, Poland
ekalb@amu.edu.pl (https://orcid.org/0000-0002-4871-2483)

Acta geographica Slovenica, 61-2, 2021
43
1 Introduction
Despite many years of research on climate change, there are no clear indications as to the direction and
intensification of precipitation variability. The scenarios and models presented in the literature all assume
a global, albeit varied, increase in air temperature. On the other hand, research results on the direction
and range of precipitation (Pr) variability in the future (including in Poland) remain burdened with much
higher uncertainty (Kundzewicz and Kozyra 2011; IPCC 2014; Kalbarczyk et al. 2018). 
Analyses of historical data that contains precipitation totals and the number of days with precipita-
tion or extreme precipitation values indicate that in the 20
th
century and at the turn of the 21
st
century
there were no clear regularities in their patterns (Halimatou, Kalifa and Kyei-Baffour 2017; Pathak et al.
2018; Caloiero, Caloiero and Frustaci 2018). Many reports frequently point to the lack of a significant trend
of precipitation totals in Europe; however, regional occurrences of both positive and negative Pr trends
have been reported (Kundzewicz, Radziejewski and Pińskwar 2006; Labudová, Faško and Ivaňáková 2015;
Łupikasza 2017). Also, previous research on the multi-year variability of Pr conducted for various regions
of Poland did not produce any unambiguous results so it is not certain how it will develop in the future
(Majewski, Przewoźniczuk and Kleniewska 2010; Żarski et al. 2014; Ilnicki et al. 2015; Ziernicka-Wojtaszek
and Kopcińska 2020). Precipitation variability occurring in Central Europe is mostly explained by its depen-
dence on atmospheric circulation, which determines the prevalence of continental or oceanic weather trends
and shapes the global and regional climates (Degirmendžić, Kożuchowski and Żmudzka 2004; Twardosz,
Niedźwiedź and Łupikasza 2011; Młyński, Cebulska and Wałęga 2018). Out of the remaining factors shap-
ing precipitation variability in Poland research studies included e.g. the importance of cloud cover and
terrain (Bokwa and Skowera 2008; Żmudzka 2009). Knowledge of precipitation variability is vital for many
sectors of the economy. The sum of precipitation and its temporal distribution affect the functioning and
development of, for example, agriculture, fisheries, forestry, water transport, hydropower generation and
tourism, thereby influencing the quality of life in a given country (Kalbarczyk, Kalbarczyk and Raszka 2011;
Marcinkowski and Piniewski 2018; Radzka, Jankowski and Jankowska 2019). Recognizing the degree of
Pr variability is essential for climate risk management (Marković et al. 2014; Šebenik, Brilly and Šraj 2017;
Młyński, Cebulska and W ałęga 2018; Stefanova et al. 2019; Ziernicka-W ojtaszek and Kopcińska 2020). Floods
resulting from sudden atmospheric precipitation are one of the biggest climatic threats to cities (Pedrozo-
Acuña et al. 2017; Szewrański et al. 2018; Olsson et al. 2019), therefore determination of precipitation trends
can be useful when planning adaptation measures to climate change for urban and rural areas (Hardoy et al.
2014; Reckien et al. 2015; Chu, Anguelovski and Roberts 2017). Knowledge of precipitation variability in
a multi-year and spatial perspective requires continuous updating, so research studies are conducted anew
for the changing climatic conditions in various regions of the world. 
The aims of this paper were to determine the temporal and spatial variability of precipitation and to
distinguish regions of Poland based on specific variability of precipitation totals.
2 Materials and methods
The paper used daily precipitation totals which were collected at 74 meteorological stations located across
Poland (Figure 1). Precipitation totals (Pr, mm) were calculated for each year in the analyzed period between
1951 and 2018 for each individual month in each of these years. The initial data were made accessible by the
Polish Institute of Meteorology and Water Management which is responsible for systematic measurements
and observations with the use of their basic network of stations and special-purpose measurement networks.
Single missing daily precipitation totals were added on the basis of complete measurement series from
the nearest stations. Longer series of missing daily totals (at least 10 days long) were determined by means
of linear or non-linear regression equations whose calculated determination coefficients described at least
a 64% fit of the empirical data to the regression function.
Precipitation patterns were described with the following indices: the mean (x ̄ ), standard deviation (SD),
variation coefficient (V), and extreme values, i.e. the minimum (MIN) and the maximum (MAX) calcu-
lated on the basis of all the analyzed annual periods and months during the entire analyzed 1951–2018
period (further accepted also as the norm). Spearman’s coefficient (r) was used to describe the linear pre-
cipitation trend. Precipitation conditions for chosen 2 years and the 24 months with the lowest and highest

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
precipitation totals were characterized by an index that expressed extreme values as a percentage of the
sum of multi-year precipitation and the average number of days without precipitation (0.0) and with pre-
cipitation in the following ranges: 0.1–1, >1, >2, >5, >10, >20 and >50 mm (Olechnowicz-Bobrowska 1970;
Bochenek 2020).
Maps presenting statistical characteristics of precipitation conditions in Poland in various time func-
tions with a borders of the 16 administrative provinces were prepared using inverse distance weighting in
ArcGIS Desktop 10.6.1 software. Due to the fact that very high precipitation variability occurs in only one
region of Poland, some maps were supplemented with a legend which does not use the same range of val-
ues in all intervals. Therefore, on the color scale the last two ranges of values were marked with grey and
black. The legend showing the linear trend of precipitation totals gives critical values of Spearman’s coef-
ficient for α≤0.1 and α≤0.01, which amount to 0.201 and 0.311, respectively.
The regions in Poland with a similar variability of precipitation were determined on the basis of hier-
archical clustering in 3 multi-year periods: 1951–1984 (the first half of the entire examined multi-year period),
1985–2018 (the second half of the entire examined multi-year period), and 1951–2018 (the whole exam-
ined multi-year period). The analysis took into consideration 24 variables: average multi-year precipitation
totals and their average multi-year standard deviation values, both of which were calculated separately for
each month for each meteorological station and each analyzed multi-year period. Before the analysis, the
values of all variables (Z) were standardized according to the equation:
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16°0'0"E 14°0'0"E
54°0'0"N
54°0'0"N
52°0'0"N
52°0'0"N
50°0'0"N
50°0'0"N
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Scale: 1:10,000,000
Content and map by: Robert Kalbarczyk
Source: IMWM (Poland), 2020
© 2020, Robert Kalbarczyk
01 0 0 50
km
Figure 1: Locations of meteorological stations used in the research study.

where x
i
is the observed value of a variable from a given station in a given month and multi-year period,
x ̄ is the arithmetic mean for all stations in a given month and multi-year period, and SD is the standard
deviation from all stations in a given month and multi-year period.
The study used an agglomerative method of clustering to classify meteorological stations into groups
so that the degree of correlation of a given station with stations from the same group would be possibly
the strongest, and with stations from the remaining groups possibly the weakest. Distances between sta-
tions in multidimensional space were calculated by means of the city block distance (Manhattan distance),
thanks to which the effect of outliers is reduced. Distances between new clusters were determined by Ward’s
method. The accepted measure of the linkage amounted to 110. The method aims to minimize the sum
of the squared deviations of any two clusters which may be formed at any stage. 
Regression and cluster analysis were carried out in STATISTICA 13.3 software. 
3 Results 
3.1 Precipitation distribution 
In 1951–2018, the average precipitation total (Pr) for the whole of Poland was approximately 634 mm
(Table 1). In some months, Pr fluctuated from approximately 31 mm in February to approximately 90 mm
in July. Pr of up to 40 mm was also recorded in January and March, and Pr of over 70 mm was recorded
in June and August. The annual standard deviation for multi-year precipitation totals amounted to ~82 mm,
but in February it was only ~13 mm, and in July as much as 34 mm. A high standard deviation of Pr, i.e.
>25 mm, was calculated for August and October. The highest variability of precipitation, expressed by vari-
ation coefficient V , was characteristic of precipitation in October (60.5%), and the lowest – precipitation
in June (27.3%), with the variability of annual precipitation sums at a level of 13%. A significant positive
increase in Pr for the whole country was found only for March (r=0.25, α≤0.05). 
In Poland, the spatial distribution of average multi-year precipitation totals was very varied (Figure 2).
The lowest Pr was observed in the central strip of Poland and amounted to <550 mm.
Precipitation increased latitudinally northwards and southwards, where the observed totals were the
highest, namely >1300 mm. In some months, the spatial structure of Pr was slightly different than for the
entire year (Figure 3). 
Acta geographica Slovenica, 61-2, 2021
45
Z =
SD
(x
i
–x ̄ )
Table 1: Characteristics of precipitation totals variability in Poland, 1951–2018.
Characteristics
Period / month x
¯ ±SD rV
January–December 634.1±82.3 0.17
ns
13.0
January 36.3±15.0 0.15
ns
41.3
February 31.3±13.1 0.04
ns
41.9
March 35.4±13.5 0.25
1
38.1
April 41.0±14.4 –0.11
ns
35.1
May 62.5±20.3 0.03
ns
32.5
June 75.8±20.7 –0.07
ns
27.3
July 89.6±34.0 0.05
ns
37.9
August 72.0±25.1 –0.09
ns
34.8
September 56.3±23.7 0.11
ns
42.1
October 46.1±27.9 0.13
ns
60.5
November 44.9±16.4 0.01
ns
36.5
December 42.7±16.3 0.04
ns
38.2
Notes: x
¯ – arithmetic mean (mm), SD – standard deviation (mm), r – Spearman’s correlation coefficient for a linear trend, V – coefficient of
variation (%), 
1 – 
significant at α≤0.05, 
ns
– non-significant at α≥0.1

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
46
Legend
precipitation [mm] 
< 550
550–600
600–650
650–700
700–750
750–800
800–1300
> 1300 
Scale: 1:10,000,000
Content and map by: Robert Kalbarczyk
Source: IMWM (Poland) 2020
© 2020, Robert Kalbarczyk
01 0 0 50
km
Figure 2: Spatial distribution of average multi-year annual precipitation totals in Poland, 1951–2018.
Figure 3: Spatial distribution of average multi-year precipitation [mm] totals by months in Poland, 1951–2018.p p. 48–49
From January to March, the lowest value of precipitation (<30mm) occurred mainly in central-east Poland;
the highest, i.e. >80–90 mm, occurred in the southern part of the country. From April to June, the lowest Pr
was observed in the Polish Plains (from <40mm in April to <60mm in May), and the highest was in the south
(from >105 mm in April to >170 mm in June). In July, Pr oscillated from <80 mm to >180 mm, with the
lowest values in the central-west and central-east parts; in August Pr oscillated from <60 to >150 mm, with
the lowest values in central-west Poland; in September Pr oscillated from <50 to >110 mm, with the low-
est values in the central-west part. In October in the central strip of Poland, which stretches horizontally,
precipitation amounted to <40 mm; in the north and south it amounted to >85 mm. Finally, in November
and December, a Pr of <40mm occurred in central-east Poland, and a Pr of >90–95mm occurred in the south.
3.2 Variability and precipitation trend
In 1951–2018, the annual standard deviation of Pr for whole of Poland fluctuated from <100 to >210 mm
(Figure 4).
In the areas with the highest annual precipitation totals, the calculated standard deviation values (SD)
were also the highest. In particular months, the standard deviation of Pr oscillated from <15 mm in January
to >90 mm in July (Figure 5). 
Figure 5: Spatial distribution of the standard deviation for monthly precipitation [mm] totals in Poland, 1951–2018.p p. 50–51
The lowest SD was calculated for precipitation in 3 months: January, in some stations located in cen-
tral Poland; February, in north-east and central Poland; March, in central Poland. The highest SD in all
months was calculated for precipitation in the southern part of the country, i.e. in high-mountain areas,
and also in October in the northern part of Poland. In the analyzed multi-year period, annual precipita-
tion totals clearly decreased or increased only in some parts of Poland (Figure 6).

Acta geographica Slovenica, 61-2, 2021
47
Legend
percipitation [mm]
< 100
100–110
110–120
120–130
130–140
140–210
> 210 mm
Scale: 1:10,000,000
Content and map by: Robert Kalbarczyk
Source: IMWM (Poland), 2020
© 2020, Robert Kalbarczyk
01 0 0 50
km
Figure 4: Spatial distribution of the standard deviation for annual precipitation totals in Poland, 1951–2018.
Legend
< –0.311
–0.311– –0.201
–0.201–0.0
0.0–0.201
0.201–0.311
> 0.311
Scale: 1:10,000,000
Content and map by: Robert Kalbarczyk
Source: IMWM (Poland), 2020
© 2020, Robert Kalbarczyk
01 0 0 50
km
Figure 6: Spatial distribution of the Spearman correlation coefficient of the linear trend for annual precipitation totals in Poland, 1951–2018.
Figure 7: Spatial distribution of the Spearman correlation coefficient of the linear trend for monthly precipitation totals in Poland, 1951–2018.p p. 52–53

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
48
< 30
30–40
40–50
50–60
60–90
> 90 January
February
March
< 30
30–40
40–50
50–60
60–90
> 90 
May
< 50
50–60
60–70
70–80
80–90
90–135
> 135
February
< 30
30–40
40–50
50–80
> 80 
April
< 40
40–50
50–60
60–70
70–105
> 105
June
< 60
60–80
80–100
100–120
120–170
> 120

Acta geographica Slovenica, 61-2, 2021
49
July
< 80
80–100
100–120
120–140
140–180
> 180
September
< 50
50–60
60–70
70–80
80–110
> 110
November
< 40
40–50
50–60
60–90
> 90
August
< 60
60–80
80–100
100–120
120–150
> 150
October
< 40
40–50
50–60
60–85
> 85
December
< 40
40–50
50–60
60–95
> 95

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
50
January
< 15
15–20
20–25
25–30
30–45
> 45 
March
< 15
15–20
20–25
25–30
30–40
> 40
< 25
25–30
30–35
35–40
40–55
> 55 May
February
< 15
15–20
20–25
25–30
30–45
> 45
April
< 20
20–25
25–30
30–45
> 45
June
< 30
30–35
35–40
40–45
45–65
> 65

Acta geographica Slovenica, 61-2, 2021
51
<40
40–45
45–50
50–55
55–60
60–90
>90 mm July
September
< 30
30–35
35–40
40–45
45–60
> 60 
November
< 20
20–25
25–30
30–35
35–45
> 45
August
< 35
35–40
40–45
45–50
50–70
> 70
October
< 30
30–35
35–40
40–50
> 50
December
< 20
20–25
25–30
30–45
> 45

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
52
–0.201–0.0
0.0–0.201
0.201–0.311
> 0.311 January
March
–0.201–0.0
0.0–0.201
0.201–0.311
> 0.311
May
< –0.311
–0.311– –0.201
–0.201–0
0–0.201
0.201–0.311
Februar
–0.311– –0.201
–0.201–0.0
0.0–0.201
0.201–0.311
April
< –0.311
–0.311– –0.201
–0.201–0.0
0.0–0.201
June
< –0.311
–0.311– –0.201
–0.201–0.0
0.0–0.201

Acta geographica Slovenica, 61-2, 2021
53
July
–0.201–0.0
0.0–0.201
0.201–0.311
September
–0.311– –0.201
–0.201–0.0
0.0–0.201
0.201–0.311 
November
–0.311– –0.201
–0.201–0.0
0.0–0.201
August
–0.311– –0.201
–0.201–0.0
0.0–0.201
0.201–0.311
October
–0.201–0.0
0.0–0.201
0.201–0.311
> 0.311 
December
–0.311– –0.201
–0.201–0.0
0.0–0.201
0.201–0.311 

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
A significant (at least at a level of α≤0.1) positive Spearman’s coefficient of ≥0.201 that was calculat-
ed for Pr was found, for example, in Masovia region (central-east), Roztocze region (south-east) and the
central part of the Slovincian Coast (north-east). A significant negative Spearman’s coefficient was found
in small areas of south-west Poland. 
In March, a significant positive increase in Pr was found in northern and central Poland (Figure 7).
An increase in Pr was found for 8 months, mainly in northern and eastern Poland: January, February, May,
July, August, September, October and December. A significant decrease in Pr in 1951–2018 was proved
in a small area of the country, mainly in western and southern Poland, also in 8 months: February, April,
May, June, August, September, November and December.
3.3 The lowest and highest precipitation
The lowest and highest annual precipitation totals in the entire analyzed multi-year period were respec-
tively recorded in 1982 and 2010, amounting to approximately 454 and 852 mm (Figure 8). 
In subsequent months of the year (Figure 9), the highest Pr values in some months occurred in dif-
ferent years than the lowest totals. The lowest annual precipitation total in Poland, which was recorded
in 1982, constituted ~72% of the multi-year precipitation average (Table 2).
In that dry year, precipitation was not recorded on ~233 days. For ~53 days, Pr values were within a range
of 0.1–1 mm, and for ~79 days they were >1 mm. In 1982, the average number of days with precipitation
of >5, >10, >20 and >50 mm amounted to 27.9, 10.0, 2.4 and 0.1 days, respectively. In some months,
54
0
100
200
300
500
600
700
900
800
Pr (mm)
Ye a r
mean the highest the lowest
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
2011
2014
2017
Figure 8: Temporal distribution of annual (January–December) precipitation totals in Poland, 1951–2018.
Figure 9: Temporal distribution of monthly precipitation totals in Poland, 1951–2018.p p. 55–57

Acta geographica Slovenica, 61-2, 2021
55
Pr (mm)
April
Y ear
mean the highest the lowest
0
20
40
60
80
100
Pr (mm)
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
2011
2014
2017
January
Pr (mm)
March
Y ear
mean the highest the lowest
0
20
40
60
80
100
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
2011
2014
2017
Y ear
mean the highest the lowest
0
20
40
60
80
100
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
2011
2014
2017
February
Y ear
mean the highest the lowest
0
20
40
60
80
100
Pr (mm)
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
2011
2014
2017

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
56
Y ear
mean the highest the lowest
0
20
40
60
80
100
Pr (mm)
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
2011
2014
2017
June
August
Y ear
mean the highest the lowest
0
20
40
60
80
100
Pr (mm)
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
2011
2014
2017
May
Y ear
mean the highest the lowest
0
20
40
60
80
100
Pr (mm)
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
2011
2014
2017
Pr (mm)
July
Y ear
mean the highest the lowest
0
20
40
60
80
100
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
2011
2014
2017

Acta geographica Slovenica, 61-2, 2021
57
Y ear
mean the highest the lowest
0
20
40
60
80
100
Pr (mm)
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
2011
2014
2017
October
December
Y ear
mean the highest the lowest
0
20
40
60
80
100
Pr (mm)
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
2011
2014
2017
September
Pr (mm)
Y ear
mean the highest the lowest
0
20
40
60
80
100
Pr (mm)
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
2011
2014
2017
November
Y ear
mean the highest the lowest
0
20
40
60
80
100
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
2011
2014
2017

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
Pr constituted only about 6% of the norm in October (in 1951) to about 51% of the norm in June (1976).
In the months of the lowest Pr, the average number of days without precipitation fluctuated from 22 days
in June (1976) to 29 days in October (1951). The average number of days with precipitation within a range
of 0.1–1 mm oscillated from 1.2 days in October (1951) to 6.6 days in January (1997). On the other hand,
the average number of days with precipitation of >1 mm fluctuated from 0.8 days in October (1951) to 5.6
days in June (1976); the average number of days with precipitation of >2 mm varied from 0.3 to 4.7 days in
October (1951) and June (1976), respectively. Higher Pr values, i.e. >5 mm, in dry months were observed
much more rarely as the average number of days with such precipitation oscillated between 0.1 and 2.8 days.
The spatial distribution of the lowest annual and monthly precipitation totals in Poland is presented
in Figures 10 and 11. In 1982, the totals fluctuated from <400 mm in central-west and central-east Poland
to >1200 mm in the south (Figure 10). The lowest Pr values, which were recorded in 1982, were on aver-
age 150 mm lower than in the multi-year period of 1951–2018 (Figure 2). In particular dry months, Pr
values oscillated from <5 mm to >105 mm (Figure 11). 
Depending on the month, precipitation of <5 mm was recorded mainly in the cold half of the year in
various parts of Poland, namely in the strip stretching from the north-west to the central-east (January
1997), in the east (February 1976), in the south-east (March 1974), in the central strip stretching from the
north to the south (April 2009), in most of the country (October 1951), in the south and the central strip
situated along the west-east axis (November (2011) and mainly in central-east Poland (December 1972).
On the other hand, Pr of >105 mm occurred in May (1956) and June (1976) in the south of Poland. In
other dry months, the highest Pr was recorded in different parts of Poland, e.g. >15 mm in February (1976)
in central-west Poland, >25 mm in April (2009) in the south-east, >60 mm in September (1959) in the north,
and >70 mm in November (2011) in the north-west. 
The highest annual Pr in Poland was registered in 2010 and constituted ~135% of the norm (Table 3).
58
Legend
precipitation [mm] 
< 400
400–500
500–600
600–700
700–800
800–1200
> 1200
Scale: 1:10,000,000
Content and map by: Robert Kalbarczyk
Source: IMWM (Poland), 2020
© 2020, Robert Kalbarczyk
01 0 0 50
km
Figure 10: Spatial distribution of the lowest annual precipitation totals in Poland in all the analyzed years, 1951–2018.
Figure 11: Spatial distribution of the lowest monthly precipitation [mm] totals in Poland in all the analyzed months, 1951–2018.p p. 60–61

Acta geographica Slovenica, 61-2, 2021
59
Table 2: Characteristics of the structure of the lowest precipitation totals in Poland, 1951–2018.
Period / month Year with the lowest % of multi-year Average number of days without precipitation and with precipitation
precipitation totals precipitation total
0.0 0.1–1 >1 >2 >5 >10 >20 >50
(mm)
January–December 1982 71.6 232.5 53.4 79.1 57.8 27.9 10.0 2.4 0.1
January 1997 20.5 22.7 6.6 1.7 1.0 0.3 0.1 0.0 0.0
February 1976 15.2 24.5 3.0 1.5 0.8 0.1 0.0 0.0 0.0
March 1974 21.4 26.7 2.4 1.9 1.3 0.4 0.0 0.0 0.0
April 2009 15.9 27.3 1.4 1.3 0.9 0.3 0.2 0.0 0.0
May 1956 44.7 22.3 3.4 5.3 3.8 1.4 0.6 0.1 0.0
June 1976 50.5 22.0 2.4 5.6 4.7 2.8 1.2 0.1 0.0
July 2006 28.6 25.4 2.3 3.3 2.7 1.5 0.8 0.2 0.0
August 2015 22.5 25.3 2.6 3.1 2.2 0.9 0.3 0.1 0.0
September 1959 25.6 22.6 3.6 3.8 2.3 0.6 0.1 0.0 0.0
October 1951 6.4 29.0 1.2 0.8 0.3 0.1 0.0 0.0 0.0
November 2011 11.1 25.7 3.4 0.9 0.5 0.1 0.0 0.0 0.0
December 1972 15.8 24.0 5.0 2.0 1.0 0.1 0.0 0.0 0.0
Table 3: Characteristics of the structure of the highest precipitation totals in Poland, 1951–2018.
Period / month Year with the highest % of multi-year Average number of days without precipitation and with precipitation
precipitation totals precipitation total
0.0 0.1–1 >1 >2 >5 >10 >20 >50
(mm)
January–December 2010 134.4 180.7 66.6 117.7 91.5 50.3 22.1 7.2 0.9
January 2007 245.3 6.0 8.2 16.8 12.1 5.6 2.0 0.3 0.0
February 2002 184.1 10.6 5.5 11.9 8.5 4.0 1.0 0.1 0.0
March 1994 207.2 8.6 6.9 15.5 11.6 4.7 1.2 0.0 0.0
April 1970 190.1 10.7 6.7 12.6 9.6 5.6 2.3 0.3 0.0
May 2010 246.0 8.8 4.9 17.3 14.7 9.3 4.4 1.6 0.2
June 2009 160.7 9.2 5.8 15.0 12.2 7.8 4.1 1.0 0.1
July 2011 200.3 10.8 4.8 15.4 13.5 9.9 6.2 2.5 0.2
August 2006 220.1 9.8 5.2 16.0 13.7 8.9 5.2 2.1 0.2
September 2001 203.4 10.0 5.3 14.7 12.2 7.3 3.7 1.0 0.0
October 1974 354.9 7.5 6.2 17.3 14.8 10.1 5.7 1.8 0.1
November 2010 201.4 9.5 6.5 14.0 11.3 6.4 2.6 0.3 0.0
December 2005 186.3 8.4 7.8 14.8 11.3 5.2 1.9 0.2 0.0

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
60
January 1997
< 5
5–10
10–15
15–20
20–25
> 25
< 5
5–10
10–15
15–20
20–25
> 25
March 1974
May 1956
< 20
20–40
40–60
60–80
80–105
> 105
February 1976
< 5
5–10
10–15
> 15
April 2009
< 5
5–10
10–15
15–20
20–25
> 25
June 1976
< 20
20–40
40–60
60–80
80–105
> 105

Acta geographica Slovenica, 61-2, 2021
61
July 2006
< 15
15–30
30–45
45–60
60–75
> 75
September 1959
< 10
10–20
20–30
30–40
40–60
> 60
November 2011
< 5
5–10
10–15
15–20
20–70
> 70
August 2015
< 10
10–20
20–30
30–40
40–55
> 55 
October 1951
< 5
5–10
> 10
December 1972
< 5
5–10
> 15

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
In wet 2010 year, no precipitation was registered on ~181 days. In 2010, the average number of days
on which precipitation was registered in Poland was the following: >1 mm (~118 days), >2 mm (~92 days),
>5 mm (~50 days), >10 mm (~22 days), >20 mm (~7 days), and >50 mm (~1 day). The highest monthly
Pr ranged from about 164% of the multi-year precipitation in June (2009) to as much as approximately
355% in October (1974). In both these months, there was no rain only for 8–9 days. Precipitation of >1 mm
per day was observed on about 15 and 17 days in June and October, respectively: >5 mm – about 8 and
10 days, >10 mm – about 4 and 6 days, and >20 mm – about 1 and 2 days. 
In 2010, which has the highest Pr in the multi-year period, precipitation fluctuated from <750 mm in
the central strip and the north to >1700 mm in the south of Poland (Figure 12). 
The highest Pr in consecutive months of the year was observed in various parts of Poland, most fre-
quently in the south (Figure 13). High precipitation values also occurred in the north (e.g. in January 2007
and October 1974), in the north-west (e.g. in February 2002 and April 1970), in the north-east (e.g. in August
2006 and October 1974) and in the east (e.g. in August 2006 and October 1974). The biggest differences
in Pr occurred in May, when the totals oscillated from <100 to >375 mm, and July when the totals oscil-
lated from <100 to >320mm; the highest totals were recorded in the southern and eastern parts of the country.
3.4 Precipitation regions 
In Poland, the area of each of the three regions (separated based on precipitation totals and precipitation
variability) changed depending on the analyzed multi-year period (Figure 14). 
In the first half of the examined multi-year period, i.e. in 1951–1984, the region with the lowest Pr
(Cluster I) mostly covered the central-east part of Poland; the second Pr region (Cluster II) covered
a bigger part of the country, namely the north, west and partly the south of Poland; the third Pr region
62
Legend
precepitation [mm]
< 750
750–1000
1000–1250
1250–1700
> 1700 
Scale: 1:10,000,000
Content and map by: Robert Kalbarczyk
Source: IMWM (Poland), 2020
© 2020, Robert Kalbarczyk
01 0 0 50
km
Figure 12: Spatial distribution of the highest annual precipitation totals in Poland in all the analyzed years, 1951–2018.
Figure 13: Spatial distribution of the highest monthly precipitation [mm] totals in Poland in all the analyzed months, 1951–2018.p p. 64–65

(Cluster III) encompassed a small area in the south and the south-west of Poland. In the second half of
the considered multi-year period, i.e. in 1985–2018, regions with a characteristic precipitation variabili-
ty covered slightly different areas of Poland. In 1985–2018, the first Pr region was approximately 50% larger
than in 1951–1984 and covered the entire central strip of Poland up to the north-western and north-east-
ern parts of the country. The second Pr region shrank at the cost of the first region and covered areas only
in the north and the south of the country; the third region, on the other hand, slightly shrank at the cost
of the second region. As expected, in the whole analyzed multi-year period (1951–2018) the distribution
of the distinguished precipitation regions was similar to the distributions in the first and second halves of
the entire multi-year period. In 1951–2018, the first and second Pr regions covered almost the same area
in terms of size. The first Pr region covered central Poland, while the second one covered the northern and
southern parts. The third Pr region was situated in the south and the south-west of Poland and its area was
slightly smaller than in 1951–1984.
In all the three analyzed multi-year periods, the stations of the lowest precipitation totals were classified
as the first Pr region, while the stations of the highest totals were classified as the third Pr region (Table 4).
In 1951–1984, average precipitation totals were ~550 mm in the first region, ~650 mm in the second
and ~1310 mm in the third; in 1985–2018 these values were ~577, ~713 and ~1237 mm, respectively. In
all the separated regions, lower Pr values in 1951–1984, in comparison with 1985–2018, occurred only in
three months: March, May and September. Comparing the two examined sub-periods, a higher average
standard deviation of Pr was calculated in 1985–2018 in Region I and Region III and in 1951–1984 in Region
II. In particular months, Pr variability determined on the basis of the standard deviation was lower in as
many as 10 months in 1951–1984 in Region II, 8 months in Region I, 6 months in Region III, and in 5
months, i.e. March, April, May, July and September, in all regions.
In the multi-year period of 1951–2018, average annual Pr oscillated from 567 mm in Region I to about
1272 mm in Region III (Table 4). In Region I, i.e. in central Poland, average monthly Pr values fluctuated
from about 28 to 82 mm; in Region II they fluctuated from about 33 to 95 mm, and in Region III they fluc-
tuated from about 73 to 172 mm; the lowest totals occurred in February and the highest were in July. The
highest variability of Pr in 1951–2018, as in the years 1951–1984 and 1985–2018, was noted in Region III.
Acta geographica Slovenica, 61-2, 2021
63
Figure 14: Regions (I, II, III) of Poland of similar precipitation totals and precipitation variability in 1951–1984, 1985–2018 and 1951–2018.p p. 66
Table 4: Characteristics (x ¯ ±SD) of precipitation totals in Poland by regions (I, II, III) in 1951–1984, 1985–2018, 1951–2018.
Period / 1951–1984 1985–2018 1951–2018
month Region Region Region
I II III I II III I II III
January–
549.7± 28.6 649.1± 58.7 1306.3± 335.9 577.1± 44.6 713.4±38.2 1236.7±352.6 567.0±36.4 693.3±41.4 1271.5±338.2
December
January 29.6±15.3 38.4±19.4 79.1±40.3 33.5±18.3 40.6±21.6 73.6±40.3 32.0±17.1 40.5±21.4 76.3±40.5
February 26.0±15.3 31.0±18.5 75.6±45.7 28.6±14.7 34.8±16.7 69.4±34.7 27.6±15.2 33.3±18.2 72.5±40.7
March 27.3±14.6 33.3±18.3 78.3±36.9 35.1±17.4 40.5±20.3 79.3±38.2 31.5±16.5 37.6±20.2 78.8±37.6
April 36.4±18.6 41.8±22.8 101.8±42.9 35.8±20.5 43.9±23.7 84.3±44.6 36.4±19.8 43.1±23.9 93.0±46.6
May 55.3±26.9 60.5±29.4 129.1±53.7 57.3±29.5 69.8±35.9 130.7±66.1 56.7±28.8 64.4±31.9 129.9±63.6
June 67.7±32.7 76.6±36.0 176.1±69.0 67.7±34.7 80.6±39.7 147.9±61.9 67.9±33.8 80.2±38.4 162.0±67.1
July 80.5±43.7 90.0±48.1 176.2±89.9 82.6±47.3 96.2±55.2 168.3±93.5 81.7±45.6 95.0±52.2 172.3±93.2
August 64.4±36.6 75.3±39.8 143.5±72.8 64.8±37.1 80.2±40.9 125.7±70.1 65.0±37.0 79.1±41.0 134.6±71.8
September 45.6±27.6 58.1±31.5 93.6±48.2 52.4±31.8 72.7±41.8 113.0±64.1 49.5±29.9 66.5±37.2 103.3±57.6
October 40.7±34.2 50.6±37.6 81.0±53.5 40.1±27.3 56.8±36.3 81.5±45.2 40.5±30.7 55.3±37.7 81.3±49.4
November 39.9±20.7 49.0±25.4 87.7±43.3 39.7±19.8 49.6±25.7 80.7±37.2 40.1±20.3 50.6±26.1 84.2±40.5
December 36.2±19.7 44.5±23.4 84.6±37.8 39.5±18.6 47.7±22.4 82.1±42.7 38.1±19.3 47.6±23.4 83.4±40.5

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
64
January
< 70
70–100
100–130
130–175
> 175
< 60
60–80
80–100
100–145
> 145
March 1994
May 2010
< 100
100–150
150–200
200–250
250–375
> 375
February 2002
< 40
40–60
60–80
80–125
> 125
April 1970
< 60
60–80
80–100
100–130
> 130
June 2009
< 80
80–110
110–140
140–170
170–210
> 210

Acta geographica Slovenica, 61-2, 2021
65
July 2011
< 100
100–150
150–200
200–250
250–320
> 320
September 2001
< 80
80–120
120–160
160–240
> 240
November 2010
< 60
60–90
90–120
120–150
> 150
August 2006
< 120
120–160
160–200
200–245
> 245
October 1974
< 120
120–160
160–200
200–240
> 240
December 2005
< 60
60–80
80–100
100–120
120–165
> 165

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
66
1951–1984
a)
1985–2018
b)
1951–2018
c)
Region
I
II
III
Scale: 1:10,000,000
Content and map by: Robert Kalbarczyk
Source: IMWM (Poland), 2020
© 2020, Robert Kalbarczyk
01 1 0 55
km

In autumn and winter months, the standard precipitation deviation was higher than in the spring and sum-
mer months and fluctuated from approximately 15 to 46 mm in Region I, from approximately 18 to 52 mm
in Region II, with the lowest values in February and the highest in July; in Region III it oscillated from
~38 mm in March to ~93 mm in July.
4 Discussion
In Poland in the multi-year period the annual precipitation totals have changed significantly only in some
areas of the country. In the south-east, central-east and north-west Poland, precipitation increased sig-
nificantly, while the sum of precipitation was only locally reduced in south-west Poland. An increase in
precipitation totals was confirmed only regionally. The observed significant positive increase in Pr in March
had the biggest spatial range. The high increase in precipitation in March and the slight increase in annu-
al precipitation totals in Poland in 1951–2013 were also confirmed by Szwed (2018).
A decrease in monthly precipitation totals was also frequent in some regions. Regional differences relat-
ed to the trends of precipitation totals and the number of days with precipitation are a very common
phenomenon. In Slovakia, regional differences in the temporal distribution of precipitation were shown
by Labudová, Faško and Ivaňáková (2015); in Czechia, some regional differentiation in annual precipita-
tion totals of daily maxima was also found (Květoň and Žák 2008). Some examples of regional differences
in precipitation variability can also be found in studies by, for example, Skowera, Kopcińska and Kopeć
(2014), Tošić et al. (2016), Kivinen et al. (2017) and Pathak et al. (2018). 
In the examined 1951–2018 period, differences between the lowest and highest values of annual and
monthly precipitation totals and the long-term average (norm) were very high. The highest annual pre-
cipitation total in Poland was recorded in 2010 and constituted ~135% of the norm. The highest monthly
precipitation total constituted from about 164% in June (2009) to as much as about 355% in October (1974)
of the multi-year monthly values. The lowest annual precipitation total in Poland, which was recorded in
1982, constituted ~72% of the multi-year annual precipitation. In particular months, precipitation totals
constituted from as little as about 6% of the monthly norm in October 1951 to about 51% of the norm in
June 1976. Although undertaken quite often, studies on values that deviate from the norm are still a chal-
lenge for researchers (Hundecha and Bárdossy 2005; Młyński, Cebulska and Wałęga 2018; Kalbarczyk and
Kalbarczyk 2020b). Differences in the extent of atmospheric precipitation in Poland are primarily
explained by the effect of certain types of atmospheric circulation; high importance is attributed to cloud
cover (Degirmendžić, Kożuchowski and Żmudzka 2004; Żmudzka 2009; Twardosz, Niedźwiedź and
Łupikasza 2011; Młyński, Cebulska and Wałęgaet 2018). For extreme phenomena it is difficult to prove
the significance of a trend and regularities in the development of a given phenomenon (Pfeifer et al. 2015;
Zeyaeyan et al. 2017). The observed differences in temporal distribution of precipitation totals between
particular years result in irregular periods of drought and excessive precipitation, whose negative social
and economic effects cannot be prevented (Kundzewicz, Radziejewski and Pińskwar 2006; Dumrul and
Kilicarslan 2017; Brázdil et al. 2019). According to some researchers, the frequency of droughts in Poland
is increasing and will continue rise until the end of the century (Kalbarczyk 2010; Kuchar and Iwański 2013;
Somorowska 2016). Similar predictions concerning the increased intensification of drought conditions until
2100 have been made for, among others, California (Pathak et al. 2018), South Europe and North Africa
(Caloiero, Caloiero and Frustaci 2018), and Thuringia in summer (Krause and Hanisch 2007). On the other
hand, North Europe is expected to experience increased precipitation (Szwed et al. 2010). It is also report-
ed that in spring Poland may expect an increase in precipitation (Mezghani et al. 2017).
Spatial distribution of annual precipitation totals in Poland shows a clear regularity. The lowest pre-
cipitation is characteristic of the central part of the country and increases northwards and southwards,
with maximum values in the southernmost mountain areas. The determined precipitation regions display
a fairly close similarity to the pluviothermal regions of Poland presented in Schmuck’s (1965) as well as
in Ziernicka-Wojtaszek and Zawora’s (2008); the fundamental difference is the range of the lowest pre-
cipitation region reaching also the north-east of the country. In the Köppen’s classification nearly the whole
Poland is located in the Dfb zone, only a small fragment in the south is included in the climatic zone Dfc
(Beck et al. 2018). Thus, the present regionalization provides additional information about spatial differ-
ences of precipitation in Poland. In particular months and seasons, spatial distribution of precipitation totals
slightly diverge from this regularity; however, the areas with the lowest precipitation totals are continually
Acta geographica Slovenica, 61-2, 2021
67

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
located in the strip of central lowlands with a shift to the west or east of the country. The highest month-
ly Pr values in the examined multi-year period occurred in various parts of the country, most frequently
in the south of Poland. This kind of spatial distribution of precipitation in Poland is consistent with pre-
vious research studies conducted on the basis of different multi-year periods, as well as research on the
early decades of the 20
th 
century (Twaróg 2016; Szwejkowski et al. 2017; Szwed 2018); this indicates sta-
ble regularities of Poland’s spatial distribution of precipitation.
The determined precipitation regions may be useful for climatic risk management and preparation of
regional and local adaptation plans aimed at balancing the effects of climate change (Twaróg 2016; Kalbarczyk
and Kalbarczyk 2020a).
5 Conclusion
In Poland, average annual precipitation totals in 1951–2018 were only ~634mm and fluctuated from <550mm
in the central part of the country to >1300 mm in the south. The lowest average monthly precipitation (Pr),
was observed in February and was about 2.9 times as low as the highest average values observed in July.
The highest variability of Pr, both annual and monthly, usually occurred in the areas of the highest pre-
cipitation totals, primarily in the south of Poland. 
In 1951–2018, in most parts of Poland apart from the south-west, annual precipitation totals rose year
by year, but a significant increase of at least at a level of α≤0.1 was found only in small areas in the north-
west, central-west and south-east. This increase was caused by the rising Pr in March which occurred mainly
in northern and central Poland.
Extreme annual precipitation totals in Poland occurred in 1982 and 2010. They constituted about 72%
and 134% of the norm, respectively. The lowest monthly Pr, which constituted only ~6% of the norm, was
recorded in October 1951; the highest monthly Pr, which constituted as much as ~355% of the norm, was
recorded in October 1974. 
In the months of the lowest Pr (dry months), the average number of days without precipitation var-
ied from about 22 days in June 1976 to 29 days in October 1951; in the months of the highest Pr (wet months),
it varied from 6 days in January 2007 to 11 days in July 2011, April 1970 and February 2002. In the months
with the lowest precipitation, the average number of days with precipitation of >5 mm and the average num-
ber of days with precipitation of >10 mm were mostly observed in June and amounted to 2.8 and 1.2 days,
respectively. Spatial distribution of the lowest and highest Pr in particular months of the year in compar-
ison with average multi-year values differed not only in precipitation totals but also in spatial distribution,
which mostly resembled a latitudinal arrangement in the case of dry months or an irregular arrangement
in wet months.
Three precipitation regions were distinguished in Poland on the basis of precipitation variability in
each of the different multi-year periods: 1951–1984, 1985–2018, and 1951–2018. The lowest and least vari-
able Pr values were classed as Region I, which in 1951–1984 covered the central-east part of Poland, whereas
in 1985–2018 it was in the central, north-west and north-east parts of the country. The highest and most
variable Pr was classed as Region III, which in all the analyzed multi-year periods was in the south-west
and south Poland. The results may prove useful while planning water management measures, as well as
in the management of flood risks and prevention of drought effects.
6 References
Beck, H. E., Zimmermann, N. E., McVicar, T. R., Vergopolan, N., Berg, A., Wood, E. F. 2018: Present and
future Köppen-Geiger climate classification maps at 1-km resolution. Scientific Data 5. DOI: https:/ /doi.org/
10.1038/sdata.2018.214
Bochenek, W . 2020: Prawidłowości obiegu wody na obszarze beskidzko-pogórskim Karpat Zachodnich na
przykładzie zlewni Bystrzanki w świetle zmian klimatu i działalności człowieka. Prace Geograficzne 271.
DOI: https://doi.org/10.7163/9788361590XXX
Bokwa, A., Skowera, B. 2008: Wpływ rzeźby i użytkowania terenu na strukturę opadów atmosferycznych w
okolicach Krakowa (1971–2005). Infrastruktura i Ekologia T erenów Wiejskich 5. Internet: http:/ /agro.icm.edu.pl/
agro/element/bwmeta1.element.agro-3a1e6917-3a41-4d29-8adc-65726f69d93c (21. 1. 2021).
68

Brázdil, R., Dobrovolný, P ., Trnka, M., Řezníčková, L., Dolák, L., Kotyza, O. 2019: Extreme droughts and
human responses to them: the Czech lands in the pre-instrumental period. Climate of the Past 15-1.
DOI: https://doi.org/10.5194/cp-15-1-2019
Caloiero, T., Caloiero, P ., Frustaci, F. 2018: Long-term precipitation trend analysis in Europe and in the
Mediterranean basin. Water and Environment Journal 32-3. DOI: https://doi.org/10.1111/wej.12346
Chu, E., Anguelovski, I., Roberts, D. 2017: Climate adaptation as strategic urbanism: assessing opportu-
nities and uncertainties for equity and inclusive development in cities. Cities 60. DOI: https://doi.org/
10.1016/j.cities.2016.10.016
Degirmendžić, J., Kożuchowski, K., Żmudzka, E. 2004: Changes of air temperature and precipitation in
Poland in the period 1951–2000 and their relationship to atmospheric circulation. International Journal
of Climatology 24-3. DOI: https://doi.org/10.1002/joc.1010
Dumrul, Y ., Kilicarslan, Z. 2017: Economic impacts of climate change on agriculture: empirical evidence
from ARDL approach for Turkey. Journal of Business, Economics and Finance 6-4. DOI: http:/ /doi.org/
10.17261/Pressacademia.2017.766 
Halimatou, T. A., Kalifa, T., Kyei-Baffour, N. 2017: Assessment of changing trends of daily precipitation
and temperature extremes in Bamako and Ségou in Mali from 1961–2014. W eather and Climate Extremes
18. DOI: https://doi.org/10.1016/j.wace.2017.09.002
Hardoy, J., Hernández, I., Pacheco, J. A., Sierra, G. 2014: Institutionalizing climate change adaptation at
municipal and state level in Chetumal and Quintana Roo, Mexico. Environment and Urbanization 26-1.
DOI: https://doi.org/10.1177/0956247813519053 
Hundecha, Y ., Bárdossy, A. 2005: Trends in daily precipitation and temperature extremes across western
Germany in the second half of the 20th century. International Journal of Climatology 25-9. DOI:
https://doi.org/10.1002/joc.1182 
Ilnicki, P ., Farat, R., Górecki, K., Lewandowski, P . 2015: Long-term air temperature and precipitation vari-
ability in the W arta River catchment area. Journal of W ater and Land Development 27. DOI: https:/ /doi.org/
10.1515/jwld-2015-0019
IMWM – Institute of Meteorology and Water Management. 2020. Internet: https:/ /danepubliczne.imgw.pl/
apiinfo (18. 05. 2021).
IPCC 2014: Climate Change 2014: Impacts, adaptation, and vulnerability. Part A: Global and sectoral aspects.
Contribution of working group II to the fifth assessment report of the Intergovernmental Panel on Climate
Change. Cambridge, New Y ork.
Kalbarczyk, E., Kalbarczyk, R. 2020a: Typology of climate change adaptation measures in Polish cities up
to 2030. Land 9-10. DOI: https://doi.org/10.3390/land9100351
Kalbarczyk, R. 2010: Temporal and spatial diversity of the occurrence of atmospheric drought in Poland
(1966–2005) and its effect of yield of pickling cucumber (Cucumis sativus L.). Spanish Journal of
Agricultural Reserach 8-4. 
Kalbarczyk, R., Kalbarczyk, E. 2020b: Meteorological conditions of the winter-time distribution of nitro-
gen oxides in Poznań: A proposal for a catalog of the pollutants variation. Urban Climate 33. DOI:
https://doi.org/10.1016/j.uclim.2020.100649 
Kalbarczyk, R., Kalbarczyk, E., Raszka, B. 2011: Risk to onion (Allium cepa L.) field cultivation in Poland
from precipitation deficiency. Notulae Botanicae Horti Agrobotanici Cluj-Napoca 39-2. DOI: https:/ /doi.org/
10.15835/nbha3926351 
Kalbarczyk, R., Kalbarczyk, E., Ziemiańska, M., Raszka, B. 2018: Assessment of air thermal conditions in
the lowland part of south-western Poland for agriculture development purposes. Atmosphere 9-6. DOI:
https://doi.org/10.3390/atmos9060215 
Kivinen, S., Rasmus, S., Jylhä, K., Laapas, M. 2017: Long-term climate trends and extreme events in Northern
Fennoscandia (1914–2013). Climate 5-1. DOI: https://doi.org/10.3390/cli5010016 
Krause, P ., Hanisch, S. 2007: Prognostic simulation and analysis of the impact of climate change on the
hydrological dynamics in Thuringia, Germany. Hydrology and Earth System Sciences Discussions 4.
DOI: https://doi.org/10.5194/hessd-4-4037-2007 
Kuchar, L., Iwański, S. 2013: Rainfall evaluation for crop production until 2050–2060 and selected climate
change scenarios for north central Poland. Infrastruktura i Ekologia Terenów Wiejskich 1. Internet:
http://www.infraeco.pl/en/art/a_17197.htm (21. 01. 2021). 
Acta geographica Slovenica, 61-2, 2021
69

Robert Kalbarczyk, Eliza Kalbarczyk, Precipitation variability, trends and regions in Poland: Temporal and spatial …
Kundzewicz, Z. W ., Kozyra, J. 2011: Ograniczanie wpływu zagrożeń klimatycznych w odniesieniu do rol-
nictwa i obszarów wiejskich. Reducing impacts of climatic threats to agriculture and rural areas. Polish
Journal of Agronomy 7. Internet: http:/ /www.iung.pulawy.pl/PJA/wydane/7/PJA7_7.pdf (21. 01. 2021).
Kundzewicz, Z. W ., Radziejewski, M., Pińskwar, I. 2006: Precipitation extremes in the changing climate
of Europe. Climate Reserach 31-1. DOI: https://doi.org/10.3354/cr031051
Květoň, V ., Žák, M. 2008: Extreme precipitation events in the Czech Republic in the context of climate change.
Advances in Geosciences 14. DOI: https://doi.org/10.5194/adgeo-14-251-2008
Labudová, L., Faško, P ., Ivaňáková, G. 2015: Changes in climate and changing climate regions in Slovakia.
Moravian Geographical Reports 23-3. DOI: https://doi.org/10.1515/mgr-2015-0019 
Łupikasza, E. B. 2017: Seasonal patterns and consistency of extreme precipitation trends in Europe, December
1950 to February 2008. Climate Research 72-3. DOI: https://doi.org/10.3354/cr01467 
Majewski, G., Przewoźniczuk, W ., Kleniewska, M. 2010: Precipitation at the meteorological station in Ursynów
WULS – SGGW in 1960–2009. Scientific Review Engineering and Environmental Sciences 48-2. Internet:
http://iks_pn.sggw.pl/PN48/A1/art1.pdf (15. 12. 2020).
Marcinkowski, P ., Piniewski, M. 2018: Effect of climate change on sowing and harvest dates of spring bar-
ley and maize in Poland. International Agrophysics 32. DOI: https://doi.org/10.1515/intag-2017-0015
Marković, S. B., Ruman, A., Gavrilov, M. B., Stevens, T., Zorn, M., Komac, B., Perko, D. 2014: Modeling of
the Aral and Caspian seas drying out influence to climate and environmental changes. Acta geographica
Slovenica 54-1. DOI: https://ojs.zrc-sazu.si/ags/article/view/1907/1658
Mezghani, A., Dobler, A., Haugen, J. E., Benestad, R. E., Parding, K. M., Piniewski, M., Kardel, I., Kundzewicz,
Z. W . 2017: CHASE-PL Climate Projection dataset over Poland – Bias adjustment of EURO-CORDEX
simulations. Earth System Science Data 9. DOI: https://doi.org/10.5194/essd-9-905-2017 
Młyński, D., Cebulska, M., Wałęga, A. 2018: Trends, variability, and seasonality of maximum annual daily
precipitation in the Upper Vistula Basin, Poland. Atmosphere 9-8. DOI: https:/ /doi.org/10.3390/atmos9080313
Olechnowicz-Bobrowska, B. 1970: Częstość dni z opadem w Polsce. Prace Geograficzne 86.
Olsson, J., Södling, J., Berg, P ., Wern, L., Eronn, A. 2019: Short-duration rainfall extremes in Sweden:
A regional analysis. Hydrology Research 50-3. DOI: https://doi.org/10.2166/nh.2019.073 
Pathak, T. B., Maskey, M. L., Dahlberg, J. A., Kearns, F ., Bali, K. M., Zaccaria, D. 2018: Climate change trends
and impacts on California agriculture: a detailed review. Agronomy 8-3. DOI: https:/ /doi.org/10.3390/
agronomy8030025
Pedrozo-Acuña, A., Jorge, A., Magos-Hernández, J. A., Sánchez-Peralta, J. A., Amaro-Loza, A., Breña-Naranjo,
A. 2017: Real-time and discrete precipitation monitoring in Mexico City: implementation and appli-
caton. International Symposium and Exhibition on Hydro-Environment Sensors and Software.
Madrid. 
Pfeifer, S., Bülow, K., Gobiet, A., Hänsler, A., Mudelsee, M., Otto, J., Rechid, D., Teichmann, C., Jacob, D.
2015: Robustness of ensemble climate projections analyzed with climate signal maps: seasonal and
extreme precipitation for Germany. Atmosphere 6-5. DOI: https://doi.org/10.3390/atmos6050677
Radzka, E., Jankowski, K., Jankowska, J. 2019: Effects of rainfall shortage and climatic water balance on
agriculture. Applied Ecology and Environmental Research 17-4. DOI: https://doi.org/10.15666/aeer/
1704_76677678 
Reckien, D., Flacke, J., Olazabal, M., Heidrich, O. 2015: The influence of drivers and barriers on urban
adaptation and mitigation plans–an empirical analysis of European cities. PLoS ONE 10-8. DOI:
https://doi.org/10.1371/journal.pone.0135597
Schmuck, A. 1965: Regiony pluwiotermiczne Polski. Czasopismo Geograficzne 36-3.
Skowera, B., Kopcińska, J., Kopeć, B. 2014: Changes in thermal and precipitation conditions in Poland in
1971–2010. Annals of Warsaw University of Life Sciences – SGGW , Land Reclamation 46-2. DOI:
https://doi.org/10.2478/sggw-2014-0013
Somorowska, U. 2016: Changes in drought conditions in Poland over the past 60 years evaluated by the
Standardized Precipitation-Evapotranspiration Index. Acta Geophysica 64. DOI: https:/ /doi.org/10.1515/
acgeo-2016-0110
Stefanova, A., Hesse, C., Krysanova, V ., Volk, M. 2019: Assessment of Socio-Economic and Climate Change
Impacts on Water Resources in Four European Lagoon Catchments. Environmental Management 64.
DOI: https://doi.org/10.1007/s00267-019-01188-1 
70

Szewrański, S., Chruściński, J., Kazak, J., Świąder, M., Tokarczyk-Dorociak, K., Żmuda, R. 2018: Pluvial
flood risk assessment tool (PFRA) for rainwater management and adaptation to climate change in newly
urbanised areas. Water 10-4. DOI: https://doi.org/10.3390/w10040386 
Szwed, M. 2018: Variability of precipitation in Poland under climate change. Theoretical and Applied
Climatology 135. DOI: https://doi.org/10.1007/s00704-018-2408-6 
Szwed, M., Karg, G., Pińskwar, I., Radziejewski, M., Graczyk, D., Kędziora, A., Kundzewicz, Z. W . 2010:
Climate change and its effect on agriculture, water resources and human health sectors in Poland. Natural
Hazards and Earth System Sciences 10. DOI: https://doi.org/10.5194/nhess-10-1725-2010 
Szwejkowski, Z., Kuchar, L., Dragańska, E., Cymes, I., Cymes, I. 2017: Current and future agroclimate
conditions in Poland in perspective of climate change. Acta Agrophysica 24-2. Internet: http:/ /www.acta-
agrophysica.org/Current-and-future-agroclimate-conditions-in-Poland-in-perspective-of-climate-
change,105059,0,2.html (15. 2. 2020). 
Šebenik, U., Brilly, M., Šraj, M. 2017: Drought analysis using the standardized precipitation index (SPI).
Acta geographica Slovenica 57-1. DOI: https://doi.org/10.3986/AGS.729
Tošić, I., Zorn, M., Ortar, J., Unkašević, M., Gavrilov, M. B., Marković, S. B. 2016: Annual and seasonal
variability of precipitation and temperatures in Slovenia from 1961 to 2011. Atmospheric Research 168.
DOI: https://doi.org/10.1016/j.atmosres.2015.09.014
Twardosz, R., Niedźwiedź, T., Łupikasza, E. 2011: The influence of atmospheric circulation on the type
of precipitation (Krakow, southern Poland). Theoretical and Applied Climatology 104. DOI:
https://doi.org/10.1007/s00704-010-0340-5
Twaróg, B. 2016: Characteristics of long-term variability of precipitation in the territory of Poland based
on GPCC data for the years 1901–2010. IOSR Journal of Environmental Science, Toxicology and Food
Technology 10-10. DOI: https://doi.org/10.9790/2402-1010015064
Żarski, J., Dudek, S., Kuśmierek-Tomaszewska, R., Bojar W ., Knopik, L., Żarski, W . 2014: Agroklimatyczna
ocena opadów atmosferycznych okresu wegetacyjnego w rejonie Bydgoszczy. Agro-climatological
assessment of the growing season rainfall in the Bydgoszcz region. Infrastructure and Ecology of
Rural Areas 2-3. Internet: http://dx.medra.org/10.14597/infraeco.2014.2.2.047 (15. 12. 2020).
Zeyaeyan, S., Fattahi, E., Ranjbar, A., Vazifedoust, M. 2017: Classification of rainfall warnings based on
the TOPSIS method. Climate 5-2. DOI: https://doi.org/10.3390/cli5020033 
Ziernicka-Wojtaszek A., Zawora T. 2008: Regionalizacja termiczno-opadowa Polski w okresie globalnego
ocieplenia. Acta Agrophysica 11-3. Internet: http://www.acta-agrophysica.org/Thermal-precipita-
tion-regionalisation-of-poland-during-the-global-warming-period,107594,0,2.html (21. 01. 2021).
Ziernicka-Wojtaszek, A., Kopcińska, J. 2020: Variation in atmospheric precipitation in Poland in the years
2001–2018. Atmosphere 11-8. DOI: https://doi.org/10.3390/atmos11080794
Żmudzka, E. 2009: Współczesne zmiany klimatu Polski. Acta Agrophysica 13-2. Internet: http:/ /www.old.acta-
agrophysica.org/artykuly/acta_agrophysica/ActaAgr_167_2009_13_2_555.pdf (21. 01. 2021).
Acta geographica Slovenica, 61-2, 2021
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