Calculation of cooling degree days (CDDs) and hours (CDHs) is one of the simplest methods to describe the effect of outside air temperature on building cooling energy consumption. Calculations of CDD numbers and analysis of trends were performed using 10-year data of outdoor temperature, measured at the meteorological station in Riga (Latvia). Values of CDDs and CDHs for seven base temperatures (from 19.0°C to 26.0°C) are provided in a tabular form. Results showed an increase in CDDs by the year 2020. Findings of this study could be further used for energy management in Riga region.