Climate is usually defined as the average atmospheric conditions at a particular place over 30 years and described by mean values and variability of relevant quantities. These quantities are most often surface variables such as air temperature, amount of precipitation, air pressure, and wind. In today's climate statistics, the standard reference period is 1961 to 1990. The next standard reference period will be 1991 to 2020 and be used from 2021 on.
At the beginning of the 20th century, Wladimir Köppen discovered that particular plant communities require specific temperature and precipitation conditions to grow. Defining threshold values for monthly mean temperatures and precipitation, Köppen was able to create a system of classificiation in which he distinguished specific climate types and subtypes.
The image below shows the climate diagram for Cottbus based on Köppen's climate classification.