National Weather ServiceIllinoisFrost AdvisoryArchive to October 1, 2026
Frost Advisories in Illinois
The National Weather Service issued 16 frost advisories for Illinois in 2025 and 20 a year on average in 2008-2025; in 2021-2025 it had the 16th most of any state. 2026 through September: 9, 18% below the average of 11 for those months in 2008-2025. Winnebago was covered most often (64 times since 2008).
How many frost advisories does Illinois get?
Every frost advisory that covered part of Illinois. 2026 is an outline: the year is not over.
The numbers
| Year | Count |
|---|---|
| 2026 (through September) | 9 |
| 2025 | 16 |
| 2024 | 20 |
| 2023 | 23 |
| 2022 | 26 |
| 2021 | 26 |
| 2020 | 27 |
| 2019 | 13 |
| 2018 | 23 |
| 2017 | 11 |
| 2016 | 19 |
| 2015 | 11 |
| 2014 | 17 |
| 2013 | 21 |
| 2012 | 18 |
| 2011 | 32 |
| 2010 | 31 |
| 2009 | 15 |
| 2008 | 7 |
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 |
|---|---|---|---|
| Winnebago | 64 | 10 | May 7, 2026 |
| Boone | 62 | 10 | May 7, 2026 |
| McHenry | 62 | 9 | May 7, 2026 |
| Ogle | 60 | 10 | May 7, 2026 |
| Kane | 58 | 9 | May 7, 2026 |
| Jo Daviess | 57 | 9 | May 11, 2026 |
| Stephenson | 57 | 10 | May 11, 2026 |
| Lee | 55 | 8 | May 7, 2026 |
| Pope | 55 | 8 | October 24, 2025 |
| Carroll | 54 | 8 | May 7, 2026 |
| Hardin | 54 | 7 | October 24, 2025 |
| Johnson | 54 | 7 | October 24, 2025 |
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 frost advisory?
A frost advisory means frost is expected on clear, calm nights during the growing season, with temperatures a few degrees above freezing. 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.