National Weather ServiceIllinoisFlash Flood WatchArchive to October 1, 2026
Flash Flood Watches in Illinois
The National Weather Service issued 0 flash flood watches for Illinois in 2025 and 30 a year on average in 2008-2025; in 2021-2025 it had the 18th most of any state. 2026 through September: 0, 100% below the average of 27 for those months in 2008-2025. Hancock was covered most often (96 times since 2008).
How many flash flood watches does Illinois get?
Every flash flood watch that covered part of Illinois. 2026 is an outline: the year is not over.
The numbers
| Year | Count |
|---|---|
| 2026 (through September) | 0 |
| 2025 | 0 |
| 2024 | 2 |
| 2023 | 1 |
| 2022 | 2 |
| 2021 | 23 |
| 2020 | 39 |
| 2019 | 69 |
| 2018 | 34 |
| 2017 | 23 |
| 2016 | 34 |
| 2015 | 54 |
| 2014 | 22 |
| 2013 | 29 |
| 2012 | 10 |
| 2011 | 34 |
| 2010 | 59 |
| 2009 | 45 |
| 2008 | 57 |
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
When in the year does Illinois get them?
Sum of 2008-2025; the busiest month is labelled.
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
Where in Illinois?
| County or forecast zone | Since 2008 | Since 2023 | Last issued |
|---|---|---|---|
| Hancock | 96 | 0 | October 24, 2021 |
| Mercer | 96 | 0 | October 24, 2021 |
| Rock Island | 96 | 0 | October 24, 2021 |
| Henderson | 95 | 0 | October 24, 2021 |
| McDonough | 94 | 0 | October 24, 2021 |
| Warren | 93 | 0 | October 24, 2021 |
| Henry | 89 | 0 | October 24, 2021 |
| St. Clair | 86 | 0 | July 10, 2021 |
| Monroe | 85 | 0 | July 10, 2021 |
| Madison | 83 | 0 | July 10, 2021 |
| Whiteside | 83 | 0 | June 28, 2021 |
| Jersey | 82 | 0 | July 10, 2021 |
The NWS issues these products for counties or forecast zones; a zone can be part of a county or a mountain range.
Source: Iowa Environmental Mesonet archive of National Weather Service watches, warnings and advisories (VTEC); National Weather Service. Data as of October 1, 2026.
What is a flash flood watch?
A flash flood watch means the rain or conditions that lead to flash flooding are possible in the coming hours. Since 2022 most NWS offices issue a flood watch in its place: the national count fell from 692 in 2021 to 76 in 2022, while flood watches rose from 203 to 715 (IEM archive), so compare the two together. A watch means the conditions for the hazard are possible or favourable, but it is not yet happening: be ready to act if a warning follows. The national record · Every warning type in Illinois.