Climate change on the globe has been manifested over the past few decades by, among other things, an increase in the frequency of extreme weather events, such as droughts. Drought affects millions of people around the world every year. Its effects usually appear after a long period of rainfall deficit. Based on climate projections, it is emphasized that water scarcity will be one of the most important problems in the future. Due to the importance of the increasing problem of drought, the analysis of this phenomenon in Poland was undertaken in the context of agriculture. The aim of this study was to assess the course of drought in the vegetation period during years 2001-2020 for Poland based on the Selyaninov’s coefficient (HTC). As shown in this study, the western and central parts of the country, dominated by arable land, are particularly vulnerable to drought. Due to the cyclic nature of periods classified by HTC as dry, it can be concluded that the problem of precipitation deficit for crops in Poland could get worse.

Methods of identifying dates of passing determined threshold value are of significant importance in the study of thermal growing seasons. The difficulty to determine dates of beginning and end of growing season in a given year stems from the fact that daily mean air temperature changes irregularly on a day-to-day basis often crossing the threshold value (i.e. 5°C) multiple times. The most frequently used method to identify dates of threshold value crossing is the mathematical or graphical method proposed by Gumiński in 1950 which based on monthly mean air temperature values. In the 1970s, Huculak and Makowiec presented a method using daily mean values of air temperature. It is assumed that both methods give comparative results although calculations of daily mean air temperature render more accurate results. This paper presents the comparison of these two methods. Air temperatures measurements from 1966–2005 taken at 38 weather stations located in various physiographic conditions in Poland were used.

The purpose of agrometeorological services conducted by various institutions around the world is to support decisions in the field of planning individual farmer works and agrotechnical treatments so as to fully enable the use of the prevailing weather and climatic conditions. However, the not always sufficient spatial distribution of ground measuring stations limits the possibility of the precise determination of meteorological conditions and the state of vegetation in a specific location. The solution may be the simultaneous use of both ground and satellite data, which can improve and enhance the final agrometeorological products. This paper presents examples of the use of meteorological products combining classical ground measurement and data from meteorological radars and satellites, applied in an agrometeorological service provided by the Institute of Meteorology and Water Management in Poland. Selected examples cover Wielkopolskie Province, which is a primarily agricultural region. An analysis of the course of the soil moisture index and HTC as well as differences in the PEI spatial distribution from ground and satellite data for the extremely dry growing season of 2018 are presented. The authors tried to demonstrate that combining data available from different sources may be a necessary condition for modern agriculture in the conditions of climate change.

Evapotranspiration is an important part of the water cycle and influences, for example, water management and agricultural production. The article presents temporal and spatial changes in reference evapotranspiration (ET_o) in the growing season (April–September) against the background of climatic conditions in Poland in the years 1966–2020. ET_o was calculated using the Penman–Monteith method using data from 37 meteorological stations in the network of the Institute of Meteorology and Water Management‐National Research Institute. For the growing season of April–September, the average sum of ET_o for Poland was 529 mm. In terms of spatial distribution, the values were lowest in northern Poland (Kołobrzeg, 480 mm; Lębork, 488 mm) and highest in the central lowlands (Warsaw, 570 mm; Poznań, 566 mm). For individual months, the average sum of ET_o ranged from 53 to 63 mm in April and September to 108–112 mm in June and July. In Poland, in the years 1966–2020, ET_o showed a statistically significant upward trend of 16.4 mm/10 year. This is the result of, inter alia, statistically significant increases in sunshine duration and air temperature and a decrease in relative humidity (respectively: 62 h/10 year, 0.40°C/10 year and −1%/10 year) during the growing season in Poland. Within the multiyear study period, the maximum ET_o values occurred in 2018, reaching values of >700 mm. At that time, Poland was under the influence of very intense anticyclonic circulation. This is confirmed by the relationship between ET_o and the anticyclonic circulation index for central Poland, which is statistically significant for the 55 study years.

Information is nowadays one of the crucial elements of contemporary life, and its accessibility affects frequently the possibility of decision making and management – at the top administration level as well as at the level of a particular system user. Modern agriculture, as other spheres of activity, needs actual information supporting end users (farmers and agricultural advisors) in their decisions and activities. Agrometeorological services facilitates better use of meteorological conditions in planning individual works and more efficient plant protection. Furthermore this data can lead also to yield increase. In Poland, the agrometeorological service is provided by the Institute of Meteorology and Water Management – National Research Institute (IMGW-PIB). In the article, the Polish Agrometeo service and its planned development is described in details. Also some problems and recommendations concerning the service development are listed.