191
Recorded events
1
Direct deaths
0
Direct injuries
$1.5B
Property damage
Flash Flood in Cook County, Illinois: 191 recorded events between 1996 and 2026. The strongest on record measured 0. That places the county #48 nationally and #1 statewide for this hazard.
Decade by decade
Flash Flood in Cook County, Illinois: events per decade
Reporting practice changed over time — early decades are undercounted, not calmer.
The busiest decade for flash flood in Cook County is the 2010s, when 76 of the county's 191 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 Cook County archive, flash flood makes up 7.3% of all recorded severe weather across 8 hazard types. Nationally the county sits at #48 for this hazard and #1 within Illinois, putting it in the 98.5 percentile of all U.S. counties.
Seasonality
Events by month
Jun is the peak month for flash flood in Cook County with 45 recorded events, while Nov 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.
Significant events
Deadliest on record
| Date | Location | Scale | Deaths | Injuries | Damage |
|---|---|---|---|---|---|
| Sep 13, 2008 | BRYN MAWR | 0 | 1 | 0 | $35.0M |
Most recent
Latest recorded events
| Date | Location | Magnitude | Damage |
|---|---|---|---|
| Apr 14, 2026 | BENSENVILLE | — | $0 |
| Apr 14, 2026 | BARTLETT | — | $0 |
| Mar 15, 2026 | DOLTON | — | $0 |
| Mar 15, 2026 | (MDW) CHICAGO MIDWAY AIRPORT | — | $0 |
| Mar 6, 2026 | SOUTH CHICAGO HEIGHTS | — | $0 |
| Jan 8, 2026 | TINLEY PARK | — | $0 |
| Jan 8, 2026 | BURR RIDGE | — | $0 |
| Aug 19, 2025 | LANSING | 0 | $3.5M |
| Aug 19, 2025 | BEVERLY VIEW | 0 | $1.5M |
| Aug 18, 2025 | HEGEWISCH | 0 | $2.5M |
Other hazards here
More from Cook County
- Thunderstorm Wind 1,384
- Hail 639
- Flood 209
- Tornado 85
- Heavy Rain 61
- Lightning 57
From the record
What the reports say
Written by National Weather Service staff at the time of the event · public domain
Roughly 40,000 structures sustained flood damage around the city of Chicago. The greatest impacts were felt across the southwest side near and east of Midway Airport, but reports came in from all across the city. Chicago alone accounted for approximately $230 million in flood damages.
Heavy rain caused significant flooding and flash flooding across portions of southeast Cook County. Hundreds of roads were flooded and numerous cars were stranded in the flood waters. Some of the worst flooding occurred in and around Calumet City and Dolton where hundreds of houses and buildings were surrounded by flood waters and some streets were littered with abandoned cars. Water rescues were reported but resulted in no injuries. Hundreds of basements were flooded in Calumet City and at least 30 basements were flooded in South Holland. While the highest measured rainfall report was 5.69 inches one mile north northeast of South Holland, radar estimated rainfall showed possibly 8 to 9 inches fell across Calumet City. Other rainfall reports included 5.04 inches one mile southwest of Harvey; 4.72 inches one mile east southeast of Markham; 4.47 inches one mile southeast of Midlothian; 4.26 inches one mile south of Oak Forest and 4.14 inches in Phoenix.
Major flooding impacted portions of the souhtwest suburbs of Chicago.|Numerous streets were flooded and impassable with several feet of water in Burbank and Oak Lawn. Numerous cars stalled in the flooded streets and many basements were inundated with water. Multiple lanes and the shoulder was flooded and closed on I-294 at Route 171. Over three feet of water was reported in the viaduct at Kedzie Avenue and 79th Street where a fire truck stalled trying to pass through.
Quick answers
Frequently asked
How many flash flood events are on record in Cook County, Illinois?
191 flash flood events are recorded in Cook County between 1996 and 2026, causing 1 direct deaths.
What is the strongest flash flood recorded in Cook County?
The strongest flash flood on record in Cook County measured 0.
Where does the flash flood data for Cook 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 Cook County, Illinois.” Severe Weather History. severeweatherhistory.com/county/illinois/cook-county/flash-flood/ · Data: NOAA/NCEI, FEMA, U.S. Census — public domain.