National Weather ServiceIllinoisFlood AdvisoryArchive to October 1, 2026
Flood Advisories in Illinois
The National Weather Service issued 199 flood advisories for Illinois in 2025 and 238 a year on average in 2008-2025; in 2021-2025 it had the 21st most of any state. 2026 through September: 233, 7% above the average of 217 for those months in 2008-2025. Cook was covered most often (610 times since 2008).
How many flood advisories does Illinois get?
Every flood advisory that covered part of Illinois. 2026 is an outline: the year is not over.
The numbers
| Year | Count |
|---|---|
| 2026 (through September) | 233 |
| 2025 | 199 |
| 2024 | 173 |
| 2023 | 119 |
| 2022 | 167 |
| 2021 | 204 |
| 2020 | 217 |
| 2019 | 450 |
| 2018 | 260 |
| 2017 | 246 |
| 2016 | 204 |
| 2015 | 317 |
| 2014 | 303 |
| 2013 | 231 |
| 2012 | 64 |
| 2011 | 292 |
| 2010 | 370 |
| 2009 | 274 |
| 2008 | 192 |
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 |
|---|---|---|---|
| Cook | 610 | 129 | September 20, 2026 |
| Will | 555 | 94 | September 20, 2026 |
| La Salle | 457 | 45 | September 20, 2026 |
| Kane | 349 | 41 | September 20, 2026 |
| Grundy | 327 | 27 | August 14, 2026 |
| Winnebago | 286 | 20 | September 20, 2026 |
| Iroquois | 282 | 27 | August 20, 2026 |
| DuPage | 279 | 70 | September 20, 2026 |
| Kendall | 270 | 41 | September 20, 2026 |
| Lake | 251 | 17 | September 19, 2026 |
| Kankakee | 235 | 27 | September 20, 2026 |
| Ogle | 229 | 20 | August 11, 2026 |
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 flood advisory?
A flood advisory covers flooding that is less serious than a warning, such as water on roads or in low-lying areas, that is still a hazard to drivers and walkers. An advisory is issued for a hazard less serious than a warning that can still cause inconvenience or danger if people are not careful. The national record · Every warning type in Illinois.