Historical monthly degree days according to VDI 3807 for Germany

The historical monthly degree days are calculated from publicly available station data from the DWD Climate Data Center (CDC). The monthly degree days according to VDI 3807 are the sums of the degree days over a calendar month. The degree days refer to a room temperature of 20 degrees Celsius. Degree days are calculated as the temperature difference between room temperature and the daily mean temperature (degrees Celsius). Only the days are counted when the daily average outside temperature is less than 15 degrees Celsius (heating day). Further information: https://opendata.dwd.de/climate_environment/CDC/derived_germany/techn/monthly/heating_degreedays /hdd_3807/historical/BESCHREIBUNG_derivgermany_techn_monthly_heating_degreedays_hdd_3807_historical_de.pdf