Springfield has a humid continental climate and experiences typical mid-latitude weather. Hot, humid summers and cold, rather snowy winters are the norm. Springfield is located on the farthest reaches of Tornado Alley, and as such, thunderstorms are a common occurrence throughout the spring and summer. From 1961 to 1990 the city of Springfield averaged 35.25 inches (895 mm) of precipitation per year. During that same period the average yearly temperature was 52.4 °F (11.3 °C), with a summer maximum of 76.5 °F (24.7 °C) in July and a winter minimum of 24.2 °F (−4.3 °C) in January.
From 1971 to 2000, NOAA data showed that Springfield’s annual mean temperature increased slightly to 52.7 °F (11.5 °C). During that period, July averaged 76.3 °F (24.6 °C), while January averaged 25.1 °F (−3.8 °C).
On June 14, 1957, a tornado hit Springfield, killing two people. On March 12, 2006, the city was struck by two F2 tornadoes. The storm system which brought the two tornadoes hit the city around 8:30pm; no one died as a result of the weather. Springfield received a federal grant in February 2005 to help improve its tornado warning systems and new sirens were put in place in November 2006 after eight of the sirens failed during an April 2006 test, shortly after the tornadoes hit. The cost of the new sirens totaled $983,000. Although tornadoes are not uncommon in central Illinois, the March 12 tornadoes were the first to hit the actual city since the 1957 storm. The 2006 tornadoes followed nearly identical paths to that of the 1957 tornado.