Thermal and Precipitation Conditions during the Thermal Growing Season in Central and Northern Europe

The study analyzed thermal and precipitation conditions during the thermal growing season (TGS) in Central and Northern Europe over the period 1950–2022. The mean season length was 189 days, with substantial spatial variability ranging from 76 days in northern Scandinavia to 293 days in the southwestern part of the study area. A statistically significant increase in season length was observed over the study period. On average, the season commenced on April 24 and ended on October 30, with its onset and termination shifting towards earlier and later dates, respectively. The mean air temperature during the TGS was 12.1°C, increasing at a rate of 0.13°C/10 years, while the sum of annual temperatures rose on average by 53°C/10 years. The highest rates of change were recorded in the southern part of Central Europe. Precipitation totals during the growing season exhibited pronounced spatial and seasonal variability, with a mean value of 390 mm and a weak decreasing trend (–1.1 mm/10 years). The number of days with precipitation averaged 73, while values of the Hydrothermal Coefficient of Selyaninov (HTC) ranged from 0.5 to over 3.0, with a mean of 1.39, corresponding to optimal conditions for plant development. HTC trends were regionally differentiated but statistically insignificant for the study area as a whole. The results indicate a systematic warming of the growing season and its implications for ecosystem functioning and agricultural production in Europe.