The Cedar Valley Region of Iowa, like most regions of the Midwest, has a humid continental climate with extremes of both heat and cold. The average annual temperature at Waterloo is about 48 °F (10 °C), winters are often harsh and snowfall is common. Spring ushers in the beginning of the severe weather season. The Cedar Valley Region of Iowa averages about 50 days of thunderstorm activity per year. Tornadoes are common during the spring and summer months, with an average of 37 tornadoes in a single year. Iowa summers are known for heat and humidity, with daytime temperatures often near 90 °F (32 °C) and sometimes exceeding 100 °F (38 °C). Average winters in the state have been known to drop well below freezing, even dropping below 0 °F (−18 °C). The Cedar Valley Region of Iowa has a relatively smooth gradient of varying precipitation, receiving an average of over 34 inches of rain annually. The pattern of precipitation across Iowa is seasonal, with more rain falling in the summer months.