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Flood in Brown 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 Brown County, Illinois, between 1950 and 2026, spread over 9 years.
May is the busiest month, with 5 of the recorded events. The last 20 years account for 11 events against 7 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 5.9 per 100 square miles compares with 11.7 statewide.
NCEI attributes 1 death in the county to floods and flash floods.
Compared with Illinois
| Measure | Brown County | Illinois | US |
|---|---|---|---|
| Flood events since 1950 | 18 | 6,507 | 183,559 |
| Per 100 square miles | 5.9 | 11.7 | 5.2 |
| Per 10,000 residents | 28.0 | 5.1 | 5.5 |
| Deaths recorded | 1 | 61 | 2,961 |
| Busiest month | May | June | June |
By year
Seasonality
0Feb
0Mar
0Apr
3May
5Jun
5Jul
3Aug
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 |
|---|---|---|---|---|---|---|---|
| 1 Jul 2020 | Flash Flood | — | — | — | — | — | County |
| 11 Jul 2015 | Flash Flood | — | — | — | — | — | County |
| 15 Jun 2013 | Flash Flood | — | — | — | 1 | — | County |
| 1 Jun 2013 | Flood | — | $1K | $5K | — | — | County |
| 1 May 2013 | Flood | — | $2K | $10K | — | — | County |
| 19 Apr 2013 | Flood | — | $5K | $10K | — | — | County |
| 18 Apr 2013 | Flood | — | $1K | $5K | — | — | County |
| 25 Jun 2011 | Flash Flood | — | — | — | — | — | County |
| 13 Jun 2011 | Flash Flood | — | — | — | — | — | County |
| 25 May 2011 | Flash Flood | — | — | — | — | — | County |
| 8 Jun 2010 | Flash Flood | — | — | — | — | — | County |
| 27 Aug 2004 | Flash Flood | — | — | — | — | — | County |
| 25 Aug 2004 | Flash Flood | — | — | — | — | — | County |
| 18 Jul 2003 | Flash Flood | — | — | — | — | — | County |
| 12 May 2002 | Flood | — | — | — | — | — | Forecast zone |
| 27 Apr 2002 | Flood | — | — | — | — | — | Forecast zone |
| 8 May 1996 | Flash Flood | — | $25K | — | — | — | County |
| 1 May 1996 | Flood | — | — | — | — | — | Forecast zone |
Questions and answers
How many flood events has Brown 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 Brown County?
1 Jul 2020 (Flash Flood). Records reach NCEI about 120 days after the month ends.
What was the most damaging flood event recorded in Brown County?
The flash flood of 8 May 1996, with property damage estimated by NCEI at $25K.
How does Brown County compare with Illinois for flood?
5.9 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.