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Flood in Winnebago County, Illinois
91 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 91 flood events in Winnebago County, Illinois, between 1950 and 2026, spread over 28 years.
June is the busiest month, with 30 of the recorded events. The last 20 years account for 73 events against 18 in the 20 years before, a change that reflects reporting practice as much as weather.
The county holds 1.4% of the 6,507 flood events recorded in Illinois; its 17.7 per 100 square miles compares with 11.7 statewide.
NCEI attributes 2 deaths in the county to floods and flash floods.
Compared with Illinois
| Measure | Winnebago County | Illinois | US |
|---|---|---|---|
| Flood events since 1950 | 91 | 6,507 | 183,559 |
| Per 100 square miles | 17.7 | 11.7 | 5.2 |
| Per 10,000 residents | 3.2 | 5.1 | 5.5 |
| Deaths recorded | 2 | 61 | 2,961 |
| Busiest month | June | June | June |
By year
Seasonality
0Feb
2Mar
6Apr
3May
5Jun
30Jul
23Aug
15Sep
4Oct
2Nov
0Dec
1
Recorded events
All 91 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 |
|---|---|---|---|---|---|---|---|
| 11 Jun 2026 | Flood | — | — | — | — | — | County |
| 15 Apr 2026 | Flash Flood | — | — | — | — | — | County |
| 14 Apr 2026 | Flood | — | — | — | — | — | County |
| 18 Aug 2025 | Flash Flood | — | — | — | — | — | County |
| 25 Jul 2025 | Flood | — | — | — | — | — | County |
| 10 Jul 2025 | Flash Flood | — | $30K | — | — | — | County |
| 18 Jun 2025 | Flood | — | — | — | — | — | County |
| 18 Jun 2025 | Flood | — | — | — | — | — | County |
| 15 Jul 2024 | Flood | — | — | — | — | — | County |
| 14 Jul 2024 | Flood | — | — | — | — | — | County |
| 14 Jul 2024 | Flood | — | — | — | — | — | County |
| 14 Jul 2024 | Flash Flood | — | — | — | 1 | 1 | County |
| 14 Jul 2024 | Flash Flood | — | $500K | — | — | — | County |
| 14 Jul 2024 | Flood | — | — | — | — | — | County |
| 13 Jul 2024 | Flash Flood | — | $2.0M | — | — | — | County |
| 22 Jun 2024 | Flash Flood | — | — | — | — | — | County |
| 7 May 2024 | Flood | — | — | — | — | — | County |
| 8 Aug 2022 | Flash Flood | — | — | — | — | — | County |
| 8 Aug 2022 | Flash Flood | — | — | — | — | — | County |
| 8 Aug 2022 | Flash Flood | — | — | — | — | — | County |
| 13 May 2022 | Flash Flood | — | — | — | — | — | County |
| 9 Aug 2021 | Flood | — | — | — | — | — | County |
| 29 Jun 2020 | Flood | — | — | — | — | — | County |
| 28 Mar 2020 | Flood | — | — | — | — | — | County |
| 28 Mar 2020 | Flood | — | — | — | — | — | County |
| 6 Oct 2019 | Flood | — | — | — | — | — | County |
| 13 Sep 2019 | Flood | — | — | — | — | — | County |
| 2 Jul 2019 | Flood | — | — | — | — | — | County |
| 2 Jul 2019 | Flood | — | — | — | — | — | County |
| 14 Mar 2019 | Flood | — | — | — | — | — | County |
| 4 Oct 2018 | Flood | — | — | — | — | — | County |
| 3 Sep 2018 | Flood | — | — | — | — | — | County |
| 28 Aug 2018 | Flood | — | — | — | — | — | County |
| 26 Jun 2018 | Flood | — | — | — | — | — | County |
| 26 Jun 2018 | Flash Flood | — | — | — | — | — | County |
| 18 Jun 2018 | Flash Flood | — | $500K | — | — | — | County |
| 15 Jun 2018 | Flash Flood | — | — | — | — | — | County |
| 15 Jun 2018 | Flood | — | — | — | — | — | County |
| 9 Jun 2018 | Flash Flood | — | — | — | — | — | County |
| 21 Jul 2017 | Flash Flood | — | — | — | — | — | County |
| 29 Jun 2017 | Flood | — | — | — | — | — | County |
| 28 Jun 2017 | Flash Flood | — | $500K | — | — | — | County |
| 23 Jul 2016 | Flash Flood | — | — | — | — | — | County |
| 18 Aug 2015 | Flash Flood | — | $300K | — | — | — | County |
| 1 Aug 2014 | Flood | — | — | — | — | — | County |
| 26 Jun 2013 | Flood | — | — | — | — | — | County |
| 26 Jun 2013 | Flood | — | — | — | — | — | County |
| 22 Jun 2013 | Flood | — | — | — | — | — | County |
| 10 Mar 2013 | Flood | — | — | — | — | — | County |
| 18 Jul 2012 | Flood | — | — | — | — | — | County |
| 18 Jul 2012 | Flood | — | — | — | — | — | County |
| 26 Sep 2011 | Flood | — | — | — | — | — | County |
| 13 Aug 2011 | Flood | — | — | — | — | — | County |
| 27 Jul 2011 | Flood | — | — | — | — | — | County |
| 20 Mar 2011 | Flood | — | — | — | — | — | County |
| 13 Aug 2010 | Flood | — | — | — | — | — | County |
| 24 Jul 2010 | Flood | — | — | — | — | — | County |
| 24 Jul 2010 | Flash Flood | — | $632K | — | — | — | County |
| 11 Mar 2010 | Flood | — | — | — | — | — | County |
| 19 Jun 2009 | Flash Flood | — | — | — | — | — | County |
| 19 Jun 2009 | Flood | — | — | — | — | — | County |
| 1 Jun 2009 | Flood | — | — | — | — | — | County |
| 1 Jun 2009 | Flash Flood | — | — | — | — | — | County |
| 27 Dec 2008 | Flash Flood | — | — | — | — | — | County |
| 2 Jul 2008 | Flood | — | — | — | — | — | County |
| 1 Jul 2008 | Flood | — | — | — | — | — | County |
| 10 Jun 2008 | Flood | — | $6.0M | — | — | — | County |
| 11 Apr 2008 | Flood | — | — | — | — | — | County |
| 7 Aug 2007 | Flash Flood | — | $1.0M | — | — | — | County |
| 7 Aug 2007 | Flood | — | $2.0M | — | — | — | County |
| 18 Jul 2007 | Flash Flood | — | — | — | — | — | County |
| 18 Jul 2007 | Flash Flood | — | — | — | — | — | County |
| 18 Jun 2007 | Flash Flood | — | — | — | — | — | County |
| 4 Sep 2006 | Flash Flood | — | $20M | — | — | — | County |
| 25 Aug 2006 | Flash Flood | — | — | — | — | — | County |
| 30 May 2006 | Flood | — | — | — | — | — | County |
| 14 Feb 2005 | Flood | — | — | — | — | — | Forecast zone |
| 12 Jun 2004 | Flood | — | — | — | — | — | Forecast zone |
| 20 May 2004 | Flash Flood | — | — | — | — | — | County |
| 22 Aug 2002 | Flash Flood | — | — | — | — | — | County |
| 22 Aug 2002 | Flood | — | — | — | — | — | Forecast zone |
| 4 Jun 2002 | Flash Flood | — | — | — | — | — | County |
| 4 Jun 2002 | Flood | — | — | — | — | — | Forecast zone |
| 12 Jun 2000 | Flash Flood | — | — | — | — | — | County |
| 12 Jun 2000 | Flood | — | — | — | — | — | Forecast zone |
| 4 Jun 2000 | Flood | — | — | — | — | — | Forecast zone |
| 13 Jun 1999 | Flood | — | — | — | — | — | Forecast zone |
| 25 Jun 1998 | Flash Flood | — | — | — | — | — | County |
| 20 Feb 1997 | Flood | — | — | — | 1 | — | Forecast zone |
| 17 Jul 1996 | Flash Flood | — | — | — | — | — | County |
| 28 May 1996 | Flash Flood | — | — | — | — | — | County |
Questions and answers
How many flood events has Winnebago County had?
91 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 Winnebago County?
11 Jun 2026 (Flood). Records reach NCEI about 120 days after the month ends.
What was the most damaging flood event recorded in Winnebago County?
The flash flood of 4 Sep 2006, with property damage estimated by NCEI at $20M.
How does Winnebago County compare with Illinois for flood?
17.7 events per 100 square miles against 11.7 statewide; the county holds 91 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.