1,469 flood insurance claims·$7.8M paid·8 federal flood & hurricane disasters
Share of the whole county outline, rivers and lakes included; parts FEMA hasn’t mapped count as zero.
Shaded areas are FEMA’s mapped flood hazard zones in and around St. Clair County, Illinois. Zoomed out they are simplified; at street level the map switches to FEMA’s exact layer. Tap anywhere to check that spot, or search an address above.
Flash flooding from summer thunderstorms dominates the flood profile of St. Clair County, Illinois, accounting for 44 of the 58 recorded flood events in the NOAA Storm Events Database over the last 30 years, alongside 14 general flood events. Recent events illustrate this hazard, including multiple heavy rainfall and flash flooding episodes driven by thunderstorms along cold fronts in July 2025, as well as a stationary front that produced flash flooding on April 4, 2025.
Federal insurance claims data demonstrates that properties in high-risk riverine and coastal fringe areas face the most severe impacts. Specifically, Zone A properties account for the highest claim volume with 679 filings, averaging an $11,705 payout and an average recorded water depth of 10 inches. Meanwhile, properties mapped in Zone X experience deeper average water depths of 17 inches across 236 claims, resulting in an average payout of $8,846.
Homeowners, real estate agents, and journalists should pay the closest attention to properties located within FEMA Zone A and Zone X, where historical claim frequencies and recorded water depths indicate substantial vulnerability to both rapid flash flooding and standing water accumulation.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
41% of St. Clair County’s flood insurance claims were on properties rated outside FEMA’s high-risk zones.
1,154 NFIP claims with a recorded rated flood zone, 1978 to date. The zone is the one FEMA used to rate that policy, which may not match today’s map. Source: OpenFEMA NFIP claims.
In flood insurance claims here that reported a flood depth, the average was 10 inches.
Drawn to scale against an 80-inch door. Even a few inches soaks flooring, the bottom of the drywall and anything plugged in near the floor.
Average of the depths reported on claims (zero and implausible values left out); FEMA’s record doesn’t say exactly where each depth was measured. Source: OpenFEMA NFIP claims.
The worst year was 1993, with 299 claims and $517,000 paid, the year of Severe Storms & Flooding.
Bar height is scaled by square root so ordinary years stay visible next to the worst one. NFIP claims by year of loss. Source: OpenFEMA.
10 NOAA storm reports from St. Clair County describe what happened, in the words of the forecasters who covered it. Read the Illinois flood stories →
19 federal disaster declarations since 1968, 8 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Severe Storms, Tornadoes, Straight-line Winds, And Floodng | Jul 13, 2024 |
| Severe Storm And Flooding | Jul 25, 2022 |
| Severe Storms And Flooding | Feb 24, 2019 |
| Severe Storms And Flooding | Jun 1, 2008 |
| Severe Winter Storm | Nov 30, 2006 |
| Hurricane Katrina Evacuation | Aug 29, 2005 |
| Severe Storms, Tornadoes And Flooding | Apr 21, 2002 |
| Severe Storms And Flooding | Apr 28, 1996 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
58 since 1996: 44 flash floods and 14 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flash Flood | Jul 17, 2025 | $25,000 |
| Flash Flood | Jul 6, 2025 | $25,000 |
| Flash Flood | Jul 6, 2025 | $10,000 |
| Flash Flood | Apr 4, 2025 | $30,000 |
| Flash Flood | Jul 14, 2023 | — |
| Flash Flood | Jul 28, 2022 | — |
| Flash Flood | Jul 26, 2022 | $10.0M |
| Flash Flood | Jul 25, 2021 | — |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flash Flood · Jul 17, 2025. Numerous thunderstorms developed along and south of a cold front during the afternoon of July 17th. These thunderstorms congealed and dumped 4+ inches of rain on portions of southwest Illinois over 2 hours, resulting in flash flooding.
Flash Flood · Jul 6, 2025. Numerous thunderstorms developed along and ahead of a cold front during the late morning into early afternoon of July 6th. The high moisture/low shear environment was favorable for wet microbursts and heavy rainfall. Thunderstorms generally acted as expected given the environment, with wind damage and flash flooding occurring. A tornado also impacted western Fayette County in the late afternoon.
Flash Flood · Apr 4, 2025. A stationary front over southern Missouri along with ample mid-level forcing, moisture, and efficient rain processes resulted in flash flooding across portions of southwest and south central Illinois.
Flash Flood · Jul 14, 2023. Isolated storms developed in an area where dewpoints in the low to mid 70s pooled. There was some weak surface convergence, ML CAPEs over 2000 J/kg, and steep low-level lapse rates, so there were some localized damaging microbursts with the severe storms. An area of storms over northern St. Clair County in Illinois produced up to 5 inches of rain in about a two hour period with some reports of flash flooding.
National Weather Service narratives, lightly trimmed. Source: NOAA Storm Events Database.
Every colour on the map above is a place on this drawing: where the ground sits relative to the flood FEMA plans for.
If a building in St. Clair County is in a high-risk zone (A or V) and its mortgage comes from a federally regulated or insured lender, or is federally backed, flood insurance is required.
Outside those zones it is optional, and often worth having: from 2014 to 2024 nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area. Since Risk Rating 2.0, NFIP premiums are set for each building, so the only reliable price is a quote: FloodSmart.gov or a local agent.