40
Recorded events
0
Direct deaths
0
Direct injuries
$1.9M
Property damage
Flash Flood in Williamson County, Illinois: 40 recorded events between 1996 and 2025. The strongest on record measured 0. That places the county #826 nationally and #22 statewide for this hazard.
Decade by decade
Flash Flood in Williamson County, Illinois: events per decade
Reporting practice changed over time — early decades are undercounted, not calmer.
The busiest decade for flash flood in Williamson County is the 2010s, when 14 of the county's 40 recorded events were logged. Comparing decades is useful for spotting active periods, but the earliest years are thin because systematic reporting for this hazard began later.
Within the Williamson County archive, flash flood makes up 10.7% of all recorded severe weather across 8 hazard types. Nationally the county sits at #826 for this hazard and #22 within Illinois, putting it in the 72.5 percentile of all U.S. counties.
Seasonality
Events by month
Apr is the peak month for flash flood in Williamson County with 10 recorded events, while Sep is the quietest. Seasonality here is a property of the archive as much as the climate: reports cluster where population and spotter networks are densest.
Most recent
Latest recorded events
| Date | Location | Magnitude | Damage |
|---|---|---|---|
| Jul 19, 2025 | CAMBRIA | 0 | $0 |
| May 8, 2024 | SCOTSBORO | 0 | $0 |
| Jul 19, 2023 | CARTERVILLE | 0 | $25K |
| Aug 4, 2022 | MARION | 0 | $100K |
| Feb 17, 2022 | MARION | 0 | $0 |
| Mar 11, 2021 | MARION | 0 | $5K |
| Jul 1, 2020 | MARION | 0 | $0 |
| Jun 22, 2019 | FREEMAN SPUR | 0 | $0 |
| Jun 22, 2019 | MARION | 0 | $0 |
| Jul 16, 2018 | FREEMAN SPUR | 0 | $10K |
Other hazards here
More from Williamson County
- Thunderstorm Wind 137
- Hail 120
From the record
What the reports say
Written by National Weather Service staff at the time of the event · public domain
There were numerous reports of street flooding in Marion. Significant street flooding occurred across the city of Johnston City, where over four inches of rain fell from midnight to late morning. Poor Farm Road was washed out north of Johnston City, leaving a trench large enough to swallow a car. On the north side of Marion, fire and rescue crews assisted residents of a flooded trailer park. The park was entirely flooded, and some residents were advised to remain indoors. Main Street on the east side of the Marion square was nearly impassable. A Marion day care center was evacuated due to flooding. Several inches of water were in the classrooms and hallway. A Cocorahs observer at Marion measured 5.63 inches in a 48-hour period.
Numerous roads on the northwest side of Herrin were completely flooded and impassable. Water rescues were executed in town. In Marion, numerous roads and at least a few buildings were flooded. In Crainville, a large sinkhole opened up, forcing the evacuation of two homes. The road to the spillway at Devils Kitchen Lake was closed.
Strong to severe thunderstorms repeatedly moved across the county. One inch of rain was measured at Hurst within 45 minutes. A school in Marion sustained minor damage when water seeped into the hallways. Marion fire crews closed several city streets after cars became stranded.
Quick answers
Frequently asked
How many flash flood events are on record in Williamson County, Illinois?
40 flash flood events are recorded in Williamson County between 1996 and 2025, causing 0 direct deaths.
What is the strongest flash flood recorded in Williamson County?
The strongest flash flood on record in Williamson County measured 0.
Where does the flash flood data for Williamson County come from?
All events come from the NOAA/NCEI Storm Events Database, the federal public-domain archive of severe weather reports. Dates are UTC, damage is as reported and not inflation-adjusted, and the most recent entries may still be revised.
Cite this page
“Flash Flood in Williamson County, Illinois.” Severe Weather History. severeweatherhistory.com/county/illinois/williamson-county/flash-flood/ · Data: NOAA/NCEI, FEMA, U.S. Census — public domain.