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Flood in Washington County, Illinois
18 floods and flash floods events in the NCEI Storm Events record, 1950 to 2026. Event types counted: Flood, Flash Flood, Coastal Flood, Lakeshore Flood.
NCEI notes that Storm Data is compiled from a variety of sources including the National Weather Service, other federal, state and local agencies, the media and the public; that property and crop damage figures are estimates; and that some events are recorded by NWS forecast zone rather than by county. FEMA notes that NFIP claim records are redacted and aggregated to protect the privacy of policyholders. Storm records through 30 Jun 2026.
NCEI records 18 flood events in Washington County, Illinois, between 1950 and 2026, spread over 12 years.
April is the busiest month, with 4 of the recorded events. The last 20 years account for 10 events against 8 in the 20 years before, a change that reflects reporting practice as much as weather.
The county holds 0.3% of the 6,507 flood events recorded in Illinois; its 3.2 per 100 square miles compares with 11.7 statewide.
Compared with Illinois
| Measure | Washington County | Illinois | US |
|---|---|---|---|
| Flood events since 1950 | 18 | 6,507 | 183,559 |
| Per 100 square miles | 3.2 | 11.7 | 5.2 |
| Per 10,000 residents | 13.2 | 5.1 | 5.5 |
| Deaths recorded | 0 | 61 | 2,961 |
| Busiest month | April | June | June |
By year
Seasonality
0Feb
0Mar
3Apr
4May
3Jun
4Jul
2Aug
2Sep
0Oct
0Nov
0Dec
0
Recorded events
All 18 events, most recent first. Magnitude is hail size, tornado rating or wind speed as recorded.
| Date | Event type | Magnitude | Property damage | Crop damage | Deaths | Injuries | Geography |
|---|---|---|---|---|---|---|---|
| 29 Apr 2025 | Flood | — | — | — | — | — | County |
| 4 Apr 2025 | Flash Flood | — | — | — | — | — | County |
| 26 Jul 2022 | Flash Flood | — | $50K | — | — | — | County |
| 16 Jul 2021 | Flash Flood | — | — | — | — | — | County |
| 3 Apr 2014 | Flash Flood | — | — | — | — | — | County |
| 21 Jun 2011 | Flash Flood | — | — | — | — | — | County |
| 8 Jun 2009 | Flash Flood | — | — | — | — | — | County |
| 8 May 2009 | Flash Flood | — | — | — | — | — | County |
| 31 Mar 2008 | Flash Flood | — | — | — | — | — | County |
| 18 Mar 2008 | Flash Flood | — | — | — | — | — | County |
| 12 Mar 2006 | Flash Flood | — | — | — | — | — | County |
| 29 Aug 2003 | Flash Flood | — | — | — | — | — | County |
| 11 Jun 2003 | Flash Flood | — | — | — | — | — | County |
| 12 May 2002 | Flash Flood | — | — | — | — | — | County |
| 1 May 2002 | Flood | — | — | — | — | — | Forecast zone |
| 28 Apr 2002 | Flood | — | — | — | — | — | Forecast zone |
| 24 Jun 2000 | Flash Flood | — | — | — | — | — | County |
| 5 Aug 1998 | Flood | — | — | — | — | — | County |
Questions and answers
How many flood events has Washington County had?
18 events in the NCEI Storm Events record between 1950 and 2026. Reporting of floods and flash floods became far more complete after 1996, so early decades undercount.
When was the last recorded flood event in Washington County?
29 Apr 2025 (Flood). Records reach NCEI about 120 days after the month ends.
What was the most damaging flood event recorded in Washington County?
The flash flood of 26 Jul 2022, with property damage estimated by NCEI at $50K.
How does Washington County compare with Illinois for flood?
3.2 events per 100 square miles against 11.7 statewide; the county holds 18 of the state's 6,507 recorded events.
Provenance
NOAA NCEI Storm Events Database, yearly details files through 30 Jun 2026, public domain. County-recorded events plus zone-recorded events whose forecast zone is named for the county (marked "Forecast zone"). Population and area from the US Census Bureau (2021). Built 1 Oct 2026. See the methodology, the Flood hub and the county page.