The climate varies from continental in the South to continental-subarctic in the northern part. The climate feature is great seasonal changes from -40 °C (-31 °F) to +35 °C (95 °F). The frost-free period is only 90-100 days. Winters are very cold, with average low temperatures of −25.3 °C (−13.5 °F) in January. Winter climatically divides the area into 2 parts: The North-West with dominated frequent storms, high winds, and snowfalls and the South-East associated with clear, calm, cold weather. Summers are warm but short: the average temperature in July is +24.5 °C (76.10 °F). Lake Baikal acts as a cold source in summers and a warm source in winters before it freezes over. The amount of precipitation is not great, with annual averages of 400 millimeters (16.5 inch). July is the wettest month; January, the driest one. But mostly it depends upon the year.