Williamson County weather alerts
There are no active weather alerts for Williamson County, IL right now.
Since 2016 the National Weather Service has issued about 863 alerts that included Williamson County, roughly 86 a year. The most common is the severe thunderstorm warning (162 from 2016 to 2025). The last tornado warning was issued on March 16, 2026. 23 tornadoes have touched down in the county since 1950.
Updated from the National Weather Service · lists refresh hourly; the live map loads current alerts directly from the NWS
No warnings, watches or advisories include Williamson County at the moment. This page updates automatically when the National Weather Service issues one. Check neighboring Saline County, Franklin County, Union County, Johnson County.
Williamson County alert history
Alert events that included Williamson County or its forecast zones, from the NWS warning archive.
| Alert type | 2016–2025 | 2026 | Last issued |
|---|---|---|---|
| Severe Thunderstorm Warning | 162 | 12 | September 5, 2026 |
| Dense Fog Advisory | 88 | 3 | October 15, 2026 |
| Severe Thunderstorm Watch | 64 | 7 | July 26, 2026 |
| Wind Advisory | 63 | 6 | June 17, 2026 |
| Flood Watch | 61 | 6 | August 20, 2026 |
| Flood Advisory | 53 | 3 | July 8, 2026 |
| Tornado Watch | 53 | 6 | June 26, 2026 |
| Winter Weather Advisory | 45 | 0 | December 2, 2025 |
| Heat Advisory | 40 | 9 | September 15, 2026 |
| Flash Flood Warning | 36 | 2 | July 11, 2026 |
| Flood Warning | 35 | 1 | July 11, 2026 |
| Freeze Warning | 29 | 3 | November 8, 2026 |
| Frost Advisory | 26 | 1 | October 18, 2026 |
| Tornado Warning | 25 | 2 | March 16, 2026 |
| Extreme Heat Warning | 14 | 5 | September 1, 2026 |
| Freeze Watch | 14 | 1 | November 8, 2026 |
| Winter Storm Warning | 13 | 1 | January 24, 2026 |
| Cold Weather Advisory | 13 | 2 | January 31, 2026 |
| Winter Storm Watch | 11 | 1 | January 24, 2026 |
| Red Flag Warning | 9 | 1 | March 29, 2026 |
| Extreme Heat Watch | 5 | 2 | September 1, 2026 |
| Fire Weather Watch | 1 | 0 | October 14, 2022 |
| Extreme Cold Watch | 1 | 0 | December 23, 2022 |
| Extreme Cold Warning | 1 | 1 | January 26, 2026 |
| Ice Storm Warning | 1 | 0 | January 5, 2025 |
| High Wind Warning | 0 | 1 | March 15, 2026 |
Tornado history in Williamson County
23 tornadoes have been recorded in Williamson County since 1950, killing 21 people and injuring 407. That ranks 64 of 102 counties in Illinois. The most recent was on May 16, 2025 (rated EF4).
Strongest tornadoes in Williamson County
| Date | Rating | County | Path length | Width | Deaths | Injuries |
|---|---|---|---|---|---|---|
| December 18, 1957 | F4 | Jackson County | 28.3 mi | 300 yd | 11 | 200 |
| May 29, 1982 | F4 | Williamson County | 17 mi | 400 yd | 10 | 181 |
| May 16, 2025 | EF4 | Williamson County | 16.3 mi | 900 yd | 0 | 7 |
| November 19, 1991 | F3 | Williamson County | 1.5 mi | 70 yd | 0 | 16 |
| February 29, 2012 | EF2 | Williamson County | 14.9 mi | 300 yd | 0 | 0 |
Most recent tornadoes
| Date | Rating | County | Path length | Width | Deaths | Injuries |
|---|---|---|---|---|---|---|
| May 16, 2025 | EF4 | Williamson County | 16.3 mi | 900 yd | 0 | 7 |
| April 2, 2025 | EF1 | Williamson County | 3.3 mi | 75 yd | 0 | 0 |
| May 8, 2024 | EF0 | Williamson County | 6.6 mi | 25 yd | 0 | 0 |
| May 8, 2024 | EF1 | Jackson County | 4.6 mi | 75 yd | 0 | 0 |
| April 2, 2024 | EF1 | Williamson County | 7.6 mi | 250 yd | 0 | 0 |
About Williamson County
- Population: 67,064 (2024 estimate)
- State: Illinois
- NOAA Weather Radio SAME code: 017199 (how to use it)