Illinois Tornado & Hail Guide

Illinois averages approximately 54 tornadoes per year, ranking it among the top ten states nationally. The state’s position at the convergence zone of Gulf moisture, Great Plains dry air, and northern cold air masses creates frequent severe weather outbreaks each spring and early summer. The Chicago metro — one of the largest in the country — has been impacted by multiple significant tornado events.

Illinois Tornado Season

Illinois’s primary tornado season runs April through June, with May being the most active month. Central and southern Illinois are the most tornado-prone regions. The Metro East area (St. Louis suburbs across the river), the Decatur–Springfield corridor, and the Quad Cities area see frequent significant tornadoes. Northern Illinois, including the Chicago suburbs, sees fewer but still significant tornado events.

Illinois Hail Season

Severe hail season in Illinois runs April through August. The Chicago metro and central Illinois regularly see golf-ball to baseball-sized hail in major supercell events. Hail causes significant annual losses to both residential property and agriculture in Illinois.

Historical Significant Events

• 1925 Tri-State tornado: Crossed from Missouri through Illinois and Indiana; 695 total fatalities, with the highest death tolls in southern Illinois communities including Murphysboro (234 deaths), DeSoto, and Gorham. The tornado’s 219-mile path remains the longest in recorded U.S. history.
• 1967 Belvedere-Oak Lawn tornado (F4): 33 fatalities in the Chicago suburbs on April 21.
• 1990 Plainfield EF5: 29 fatalities; struck the southwestern Chicago suburbs.
• 2004 Utica EF2: 8 fatalities in La Salle County after a tornado struck the town of Utica.

Regional NWS Offices for Illinois

| Region | WFO | Website |

|——–|—–|———|

| Northern Illinois / Chicago | NWS Chicago | weather.gov/lot |

| Central Illinois (Lincoln) | NWS Lincoln | weather.gov/ilx |

| Southern Illinois (St. Louis area) | NWS St. Louis | weather.gov/lsx |

| Western Illinois (Quad Cities) | NWS Quad Cities | weather.gov/dvn |

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