Moldova's climate is moderately continental: the summers are warm and long, with temperatures averaging about , and the winters are relatively mild and dry, with January temperatures averaging . Annual rainfall, which ranges from around in the north to in the south, can vary greatly; long dry spells are not unusual. The heaviest rainfall occurs in early summer and again in October; heavy showers and thunderstorms are common. Because of the irregular terrain, heavy summer rains often cause erosion and river silting.