States › Illinois › Hamilton County › Flood
Flood in Hamilton County, Illinois
47 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 47 flood events in Hamilton County, Illinois, between 1950 and 2026, spread over 22 years.
July is the busiest month, with 7 of the recorded events. The last 20 years account for 31 events against 16 in the 20 years before, a change that reflects reporting practice as much as weather.
The county holds 0.7% of the 6,507 flood events recorded in Illinois; its 10.8 per 100 square miles compares with 11.7 statewide.
Compared with Illinois
| Measure | Hamilton County | Illinois | US |
|---|---|---|---|
| Flood events since 1950 | 47 | 6,507 | 183,559 |
| Per 100 square miles | 10.8 | 11.7 | 5.2 |
| Per 10,000 residents | 59.4 | 5.1 | 5.5 |
| Deaths recorded | 0 | 61 | 2,961 |
| Busiest month | July | June | June |
By year
Seasonality
3Feb
2Mar
5Apr
5May
6Jun
5Jul
7Aug
7Sep
3Oct
0Nov
0Dec
4
Recorded events
All 47 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 |
|---|---|---|---|---|---|---|---|
| 4 Aug 2025 | Flash Flood | — | $5K | — | — | — | County |
| 4 Aug 2025 | Flood | — | — | — | — | — | County |
| 19 Jul 2025 | Flood | — | — | — | — | — | County |
| 19 Jul 2025 | Flash Flood | — | $5K | — | — | — | County |
| 19 Jul 2025 | Flood | — | $10K | — | — | — | County |
| 29 Dec 2024 | Flood | — | — | — | — | — | County |
| 14 Jul 2023 | Flash Flood | — | $50K | — | — | — | County |
| 24 Mar 2023 | Flash Flood | — | — | — | — | — | County |
| 3 Mar 2023 | Flash Flood | — | $200K | — | — | — | County |
| 8 Feb 2023 | Flash Flood | — | $8K | — | — | — | County |
| 18 Jan 2023 | Flood | — | — | — | — | — | County |
| 27 Jul 2022 | Flash Flood | — | — | — | — | — | County |
| 16 Jul 2021 | Flash Flood | — | $3K | — | — | — | County |
| 30 Jun 2020 | Flash Flood | — | $5K | — | — | — | County |
| 30 Jun 2020 | Flash Flood | — | — | — | — | — | County |
| 25 Sep 2018 | Flash Flood | — | $5K | — | — | — | County |
| 8 Sep 2018 | Flash Flood | — | $40K | — | — | — | County |
| 24 Feb 2018 | Flash Flood | — | — | — | — | — | County |
| 30 Apr 2017 | Flash Flood | — | $6K | — | — | — | County |
| 16 Sep 2016 | Flood | — | — | — | — | — | County |
| 15 Aug 2016 | Flash Flood | — | $4K | — | — | — | County |
| 15 Aug 2016 | Flood | — | — | — | — | — | County |
| 13 Aug 2016 | Flood | — | — | — | — | — | County |
| 28 Dec 2015 | Flood | — | — | — | — | — | County |
| 17 Aug 2014 | Flood | — | — | — | — | — | County |
| 4 Jun 2014 | Flash Flood | — | — | — | — | — | County |
| 21 Dec 2013 | Flood | — | — | — | — | — | County |
| 1 May 2011 | Flood | — | $30K | — | — | — | County |
| 24 Apr 2011 | Flood | — | — | — | — | — | County |
| 8 May 2009 | Flash Flood | — | $10K | — | — | — | County |
| 18 Mar 2008 | Flood | — | $340K | — | — | — | County |
| 21 Jul 2006 | Flash Flood | — | — | — | — | — | County |
| 12 Mar 2006 | Flash Flood | — | — | — | — | — | County |
| 9 Mar 2006 | Flash Flood | — | $30K | — | — | — | County |
| 28 Aug 2004 | Flash Flood | — | — | — | — | — | County |
| 25 May 2004 | Flash Flood | — | — | — | — | — | County |
| 1 May 2004 | Flash Flood | — | — | — | — | — | County |
| 17 Dec 2001 | Flood | — | — | — | — | — | Forecast zone |
| 18 Jun 2000 | Flash Flood | — | — | — | — | — | County |
| 17 Jun 2000 | Flash Flood | — | — | — | — | — | County |
| 3 Apr 1999 | Flood | — | — | — | — | — | County |
| 31 Jan 1999 | Flash Flood | — | — | — | — | — | County |
| 21 Jan 1999 | Flash Flood | — | — | — | — | — | County |
| 15 Apr 1998 | Flash Flood | — | $10K | — | — | — | County |
| 8 May 1996 | Flash Flood | — | — | — | — | — | County |
| 5 May 1996 | Flash Flood | — | — | — | — | — | County |
| 28 Apr 1996 | Flash Flood | — | $100K | $40K | — | — | County |
Questions and answers
How many flood events has Hamilton County had?
47 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 Hamilton County?
4 Aug 2025 (Flood). Records reach NCEI about 120 days after the month ends.
What was the most damaging flood event recorded in Hamilton County?
The flood of 18 Mar 2008, with property damage estimated by NCEI at $340K.
How does Hamilton County compare with Illinois for flood?
10.8 events per 100 square miles against 11.7 statewide; the county holds 47 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.