Iowa, like most of the Midwest, has a humid continental climate throughout the state with extremes of both heat and
cold. The average annual temperature at Des Moines is 50 °F (10 °C); for some locations
in the north the figure is under 45 °F (7 °C). Winters are often harsh and snowfall is common.
Spring ushers in the beginning of the severe weather season. 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).
Iowa has a relatively smooth gradient of varying precipitation across the state, with areas in the southeast of the state
receiving an average of over 38 inches (97 cm) of rain annually, and the northwest of the state receiving less than 28 inches
(71 cm). The pattern of precipitation across Iowa is seasonal, with more rain falling in the summer months. In Des Moines,
roughly in the center of the state, over two-thirds of the 34.72 inches (88.2 cm) of rain falls from April through September,
and about half of the average annual precipitation falls from May through August.
Special thanks to Wikipedia for the information.