Enter any address in St. Clair County, Illinois to see its FEMA flood zone
Flash flooding from thunderstorms is the dominant flood character in St. Clair County. Between 2000 and 2023, NOAA data recorded 44 flash flood events and 14 general flood events. For example, on July 6, 2025, thunderstorms produced heavy rainfall leading to flash flooding, and on July 17, 2025, over 4 inches of rain in two hours caused flash flooding in southwest Illinois.
FEMA data shows a significant number of National Flood Insurance Program (NFIP) claims filed in St. Clair County. Zone A, typically areas with higher flood risk, has the highest number of claims at 566, with an average payout of $8,078 and an average water depth of 2.5 feet. Zone X_UNSHADED, representing moderate flood risk, has 332 claims averaging $1,963 and 0.6 feet of water. Properties in Zone A, and those in Zone X with deeper water depths, warrant the most attention.
Summary generated from NOAA storm narratives and NFIP claim data for this county. Not predictive.
10 NOAA storm reports from this county describe what happened, in the words of the meteorologists who were there.
St. Clair County, Illinois has recorded 58 flood-related events since 1996 according to NOAA's Storm Events Database, including 44 flash floods and 14 river or area floods. The county has received 19 federal disaster declarations, 8 of which involved flooding or coastal storms. Enter any address above to check its FEMA flood zone designation.
FEMA Disaster Declarations (1968–2024)
Source: OpenFEMA Disaster Declarations Summaries.
| Declaration | Type | Date |
|---|---|---|
| Severe Storms, Tornadoes, Straight-line Winds, And Floodng | Flood | Jul 13, 2024 |
| Severe Storm And Flooding | Flood | Jul 25, 2022 |
| Covid-19 | Biological | Jan 20, 2020 |
| Covid-19 Pandemic | Biological | Jan 20, 2020 |
| Severe Storms And Flooding | Flood | Feb 24, 2019 |
| Severe Storms And Flooding | Severe Storm | Jun 1, 2008 |
| Severe Winter Storm | Severe Ice Storm | Nov 30, 2006 |
| Hurricane Katrina Evacuation | Hurricane | Aug 29, 2005 |
| Severe Storms, Tornadoes And Flooding | Tornado | Apr 21, 2002 |
| Severe Storms And Flooding | Severe Storm | Apr 28, 1996 |
NOAA Storm Events Database (1996–2025)
Source: NOAA National Weather Service Storm Events Database.
| Type | Date | Damage |
|---|---|---|
| Flash Flood | Jul 17, 2025 | 25.00K |
| Flash Flood | Jul 6, 2025 | 25.00K |
| Flash Flood | Jul 6, 2025 | 10.00K |
| Flash Flood | Apr 4, 2025 | 30.00K |
| Flash Flood | Jul 14, 2023 | 0.00K |
| Flash Flood | Jul 28, 2022 | 0.00K |
| Flash Flood | Jul 26, 2022 | 10.00M |
| Flash Flood | Jul 25, 2021 | 0.00K |
| Flash Flood | Aug 12, 2020 | 0.00K |
| Flash Flood | Aug 9, 2020 | 0.00K |
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 Flood — Jul 28, 2022
A cluster of showers and thunderstorms, extending from St. Louis metro area to southeastern Missouri, moved eastward through the afternoon and early evening hours. With precipitable water values over 2 inches and warm cloud depths up to 14,000 feet thick, these storms produced very heavy rainfall, up to five inches, in a short period of time, between 2 pm and 7 pm on July 28th. Also, the soil i...
Source: NOAA National Weather Service Storm Events Database.
Source: OpenFEMA NFIP Individual Claims (2.25M records analyzed).
FEMA assigns flood zone designations to areas in St. Clair County, Illinois:
AE High Risk — 1% annual chance of flooding. Insurance required.
VE Very High Risk — Coastal flooding with wave action.
X (Shaded) Moderate Risk — 500-year floodplain.
X Low Risk — Outside major floodplains.
Properties in St. Clair County, Illinois that are in FEMA-designated Special Flood Hazard Areas (zones A and V) with federally backed mortgages are required to carry flood insurance.
Even outside high-risk zones, flood insurance is recommended. From 2014 to 2024, nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area.
Visit FloodSmart.gov to find an agent and get a quote.