Tornado Risk in St. Clair County, IL
St. Clair County's tornado history, by the numbers
59 tornado tracks have crossed St. Clair County since 1952 by NOAA's count, roughly one every 1.3 years - the High band on this site's scale. That is the 92nd percentile nationally for tornado frequency. Among 102 Illinois counties in this dataset, St. Clair County ranks 12 for how often a tornado touches down.
The number that matters more than frequency
No violent (EF4-5) tornado has been recorded in St. Clair County in NOAA's 76-year database. Of its 59 recorded tracks, 42 were weak (EF0-1) and 17 significant (EF2-3).
Shelter and safe-room economics
Illinois does not currently have a confirmed state rebate layered on top of FEMA's 75% Hazard Mitigation cost-share, so a St. Clair County homeowner should expect the full national range: $2,890-$13,280, $7,645 typical.
Power after the storm, not just shelter during it
Tornado outbreaks routinely knock out power across Illinois for days, separately from any single house getting hit. A portable battery bank keeps a fridge, phone chargers and a radio running through that gap - cheaper and faster to set up than a generator.
What St. Clair County's figure does not tell you
St. Clair County's figure is county-wide, not address-specific. St. Clair County covers about 658 square miles, so a single touch here counts the same as a single touch in a county a fraction of that size. NOAA also documents that older records undercount weaker tornadoes from before Doppler radar became standard. St. Clair County has about 251,149 residents.