List of Illinois tornadoes

These tornadoes have collectively resulted in 235 deaths.

Illinois' climate is relatively average, and is only ideal for the formation of tornadoes in certain parts of the year, especially February, March and May.

Warm air from the Southern United States can reach up into the Southern Illinois, resulting in tornadic storms.

Illinois' proximity to Lake Michigan also results in cold air moving toward the Ohio Valley, creating the "hot-cold" effect seen in the traditional Tornado Alley.

Illinois is vulnerable to tornadoes with an average of 35 occurring annually, which puts much of the state at around 5 tornadoes per 10,000 square miles (30,000 km2) annually.

Tornado damage caused by a tornado that occurred in the tornado outbreak sequence of May 25-June 1, 1917 .
The Longview School in Murphysboro , where 17 students were killed by the 1925 Tri-State tornado .