Long-term variability and trends in the characteristics of heating seasons in central Europe

The study analysed the temporal and spatial variability of the changes in the start and end dates and the length of heating seasons (HS), as well as the values of heating degree-days (HDD) in Central Europe from 1961/62 to 2020/21. For this purpose, the average daily air temperature values from 12 meteorological stations located in cities with a population ranging from 180 to 17,500 were used. It was found that the start of the seasons was later at most of the studied stations, and the end of the season was hastened across the area, which contributes to the shortening of the HS by an average of 1.46 days per decade and a decrease in HDD by 96.3°C per decade. In warmer regions of Central Europe, with a higher annual average air temperature, the season starts about 4 days earlier, is longer by about 7 days, and is characterised by a decrease of about 300°C in HDD value for every 1°C increase in average annual temperature. However, based on data from selected cities, the number of their inhabitants was not found to have a statistically significant impact on the individual parameters of the studied season.