Winter cold sum of air temperature
Sum of the amounts of negative daily averages of air temperature based on the winter half-year. The cold sum is used to assess the thermal conditions (cold) of one winter and is therefore specified in the rule for the whole winter (based in this case on the period November to March). This means: Cold sum under 100 = mild. Cold sum 100 to 199 = moderately warm. Cold sum 200 to 299 = moderately cold. Cold sum 300 and higher = strict.