Tornado Risk in Stephenson County, IL
Stephenson County, IL: what NOAA's tornado record says
21 tornado tracks have crossed Stephenson County since 1958 by NOAA's count, roughly one every 3.6 years - the Moderate band on this site's scale. That is the 53rd percentile nationally for tornado frequency. Among 102 Illinois counties in this dataset, Stephenson County ranks 69 for how often a tornado touches down.
The number that matters more than frequency
No violent (EF4-5) tornado has been recorded in Stephenson County in NOAA's 76-year database. Of its 21 recorded tracks, 17 were weak (EF0-1) and 2 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 Stephenson 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 Stephenson County's figure does not tell you
Stephenson County's figure is county-wide, not address-specific. Stephenson County covers about 564 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. Stephenson County has about 43,088 residents.