National Weather ServiceIllinoisExtreme Heat WarningArchive to October 1, 2026
Extreme Heat Warnings in Illinois
The National Weather Service issued 6 extreme heat warnings for Illinois in 2025 and 5 a year on average in 2008-2025; in 2021-2025 it had the 18th most of any state. 2026 through September: 18, 234% above the average of 5 for those months in 2008-2025. Madison was covered most often (31 times since 2008).
How many extreme heat warnings does Illinois get?
Every extreme heat warning that covered part of Illinois. 2026 is an outline: the year is not over.
The numbers
| Year | Count |
|---|---|
| 2026 (through September) | 18 |
| 2025 | 6 |
| 2024 | 6 |
| 2023 | 11 |
| 2022 | 10 |
| 2021 | 1 |
| 2020 | 0 |
| 2019 | 5 |
| 2018 | 10 |
| 2017 | 4 |
| 2016 | 6 |
| 2015 | 3 |
| 2014 | 2 |
| 2013 | 0 |
| 2012 | 8 |
| 2011 | 11 |
| 2010 | 12 |
| 2009 | 1 |
| 2008 | 1 |
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 |
|---|---|---|---|
| Madison | 31 | 10 | September 3, 2026 |
| St. Clair | 30 | 9 | September 3, 2026 |
| Williamson | 28 | 11 | September 1, 2026 |
| Jackson | 28 | 11 | September 1, 2026 |
| Union | 27 | 10 | September 1, 2026 |
| Perry | 27 | 10 | September 1, 2026 |
| Monroe | 27 | 9 | September 3, 2026 |
| Franklin | 27 | 10 | September 1, 2026 |
| Pulaski | 26 | 10 | September 1, 2026 |
| Massac | 26 | 10 | September 1, 2026 |
| Johnson | 26 | 10 | September 1, 2026 |
| Alexander | 26 | 10 | September 1, 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.
The latest extreme heat warnings for Illinois in AreaZine's record
NWS LincolnWarningSeptember 4, 2026
Extreme Heat Warning: Knox, Stark, Peoria and 17 more, IL
Expired 7:00 p.m. CDT, September 4, 2026
NWS ChicagoWarningSeptember 3, 2026
Extreme Heat Warning: Northern Cook, Central Cook and Southern Cook, IL
Expired 7:00 p.m. CDT, September 3, 2026
NWS St LouisWarningSeptember 3, 2026
Extreme Heat Warning: Greene, Macoupin, Montgomery and 36 more, IL and MO
Expired 8:00 p.m. CDT, September 5, 2026
NWS Quad Cities IAWarningSeptember 2, 2026
Extreme Heat Warning: Iowa, Johnson, Cedar and 21 more, IA and IL
Expired 7:00 p.m. CDT, September 4, 2026
NWS PaducahWarningSeptember 1, 2026
Extreme Heat Warning: Jefferson, Wayne, Edwards and 55 more, IL and IN
Expired 8:00 p.m. CDT, September 5, 2026
NWS St LouisWarningAugust 14, 2026
Extreme Heat Warning: Marion, IL
Expired 9:00 p.m. CDT, August 16, 2026
NWS PaducahWarningAugust 14, 2026
Extreme Heat Warning: Jefferson, Wayne, Edwards and 55 more, IL and IN
Expired 8:00 p.m. CDT, August 16, 2026
NWS St LouisWarningJuly 28, 2026
Extreme Heat Warning: Washington, Randolph, Crawford and 6 more, IL and MO
Expired 7:00 p.m. CDT, July 28, 2026
This list is AreaZine's record of the NWS alert feed, kept since April 6, 2026; the counts above come from the complete IEM archive.
Source: National Weather Service alerts (api.weather.gov).
What is an extreme heat warning?
An extreme heat warning means dangerous heat is expected, measured by heat index or temperature thresholds each office sets. It replaced the excessive heat warning in 2025. A warning means the hazard is happening, about to happen, or very likely: act now to protect people and property. AreaZine's counts include the excessive heat warnings issued before the change. The national record · Every warning type in Illinois.