Illinois faces significant flood risk from the Mississippi, Illinois, Des Plaines, and Fox rivers, as well as urban flash flooding in the Chicago metro. The state has experienced numerous billion-dollar flood events. The 2019 Illinois River flood set record levels and caused over $1 billion in damage. The Des Plaines River corridor northwest of Chicago is one of the most flood-prone areas in the Midwest, with Des Plaines, Elgin, and Joliet experiencing repeated inundation. Chicago's aging combined sewer system causes basement and street flooding during heavy rain events. A 2023 storm dropped over 5 inches in one hour flooding hundreds of homes. The Mississippi River creates extensive risk for western Illinois communities, with Quincy, Alton, and Cairo experiencing major flood events in 2011, 2019, and 2020. The Fox River valley through Kane and McHenry counties faces both riverine and flash flood risk. Southern Illinois including the Cache River and Big Muddy River basins experiences seasonal flooding. The state has over 1,200 NFIP-participating communities and invested $4.3 billion in the TARP deep tunnel project for stormwater management in metropolitan Chicago.
Illinois Flood Zones
FEMA Flood Zone Lookup in Illinois
Look up any address in Illinois to find its FEMA flood zone designation, insurance requirements, and base flood elevation — sourced from the official National Flood Hazard Layer.
Zone A and Zone AE along the Mississippi, Illinois, Des Plaines, and Fox rivers; Zone X (shaded) for moderate-risk areas throughout metro Chicago; Zone AO for shallow flooding in agricultural lowlands; Zone AR for levee-protected areas along the Mississippi.
Cook County, Kane County, DuPage County, Madison County, Peoria County
NFIP premiums typically range $500-$1,200 for standard-risk properties. Riverfront properties along the Des Plaines and Fox rivers can run $1,500-$3,500 annually. Chicago basement flooding risk has driven premium increases in urban neighborhoods.
Frequently Asked Questions — Illinois
Does Chicago flood?
Yes. Chicago's combined sewer system regularly causes basement and street flooding during heavy rain. The TARP deep tunnel project has reduced but not eliminated risk. The Des Plaines River also floods communities northwest of the city.
How bad are Illinois River floods?
The 2019 flood set record levels and caused over $1 billion in damage across the river valley. Communities like Peoria, Pekin, and Lacon have experienced repeated major floods along one of the most flood-prone rivers in the Midwest.
Is flood insurance expensive in Illinois?
Inland standard-risk properties may pay $500-$1,000 annually, while riverfront and flood-prone urban areas can run $1,500-$3,500. Chicago properties with basement flood risk have seen premium increases under Risk Rating 2.0.
Disclaimer: FloodZoneCheck is a free research tool using public FEMA data, not an official Standard Flood Hazard Determination. Lenders require a certified determination from a licensed provider. Zone boundaries can cross a single parcel — confirm exact risk and insurance requirements with FEMA or your insurer before relying on this for a purchase or insurance decision.
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