Tornadoes have captured the imagination of the public like no other weather phenomena. Illinois is ranked high in terms of the number of tornadoes and tornado impacts (damages, deaths, and injuries). In fact, Illinois has experienced some of the worst tornadoes in U.S. history. The infamous Tri-State tornado occurred on March 18, 1925, passing through southern Missouri, Illinois, and Indiana, leaving 695 dead and 2000 injured. The Mattoon tornado of May 26, 1917, left 101 dead and 638 injured.
On a brighter note, the first documented case of a tornado being detected by radar occurred in Illinois. On April 9, 1953, staff at the Illinois State Water Survey tracked the development, growth, and movement of a tornado, as identified by the distinctive " hook echo". This discovery led to the development of a nationwide network of radar sites in the 1950s to spot and track tornadoes.
This page provides a tornado climatology for Illinois. Items to check out are:
|Year||Number of Events||Deaths||Injuries|
**new record for Illinois
Here are Water Survey-related reports on Illinois tornadoes. They are available as PDF files.
Tornadoes were typically classified using the Fujita or F-scale, the higher the number the worse the damage. In recent years, the F-scale was changed to the EF-scale or "Enhanced Fujita"-scale. This was based on refinements to the original scale and is described in more detail by the NWS here and here. Below is the original scale.
|Scale||Wind Speeds||Typical Damage|
|F-0||40-72 mph||Light damage: some damage to chimneys; tree branches broken; sign boards damaged.|
|F-1||73-112 mph||Moderate damage: peels off some roofing; mobile homes pushed off foundation; moving cars blown off road.|
|F-2||113-157 mph||Considerable damage: roofs torn off houses; mobile home demolished; large trees snapped or uprooted; cars lifted off ground.|
|F-3||158-205 mph||Severe damage: roofs and walls blown down; trains overturned; most trees uprooted; cars lifted and tossed.|
|F-4||207-260 mph||Devastating damage: well-constructed buildings leveled; cars tossed some distance;|
|F-5||261-318 mph||Incredible damage: massive destruction; car-size objects thrown as far as 100 meters; most buildings leveled and swept away; incredible phenomena will occur.|