Flood Warning — Cook County, Illinois
Flooding is occurring or imminent along rivers, streams, or low-lying areas.
Current Status
🌊 Active: Flood Warning
Flood Warning issued August 2 at 10:29AM CDT until August 3 at 6:00PM CDT by NWS Chicago IL
...The Flood Warning continues for the following rivers in Illinois... Thorn Creek at Thornton affecting Cook County. For the Thorn Creek...including Thornton...Minor flooding is forecast. * WHAT...Minor flooding is occurring and minor flooding is forecast. * WHERE...Thorn Creek from Near Glenwood downstream to confluence with Little Calumet River, including the Thornton gauge. * WHEN...Until Monday evening. * IMPACTS...At 13.0 feet, Parking lots threatened at Glenwood Academy. * ADDITIONAL DETAILS... - At 10:00 AM CDT Sunday the stage was 12.9 feet. - Recent Activity...The maximum river stage in the 24 hours ending at 10:00 AM CDT Sunday was 13.3 feet. - Forecast...The river has crested and is expected to fall below flood stage early tomorrow afternoon. - Flood stage is 9.0 feet. - http://www.weather.gov/safety/flood
Effective August 2, 2026 at 11:29 AM ET · Expires August 3, 2026 at 5:30 AM ET
Event Details
Event Type
Flood Warning
Severity
severe
Issued By
NWS Chicago IL
Expires
August 3, 2026 at 5:30 AM ET
Last Checked
2 minutes ago
What To Do
📋 Official NWS Guidance
A Flood Warning means water levels above flood stage are imminent or may already be occurring. Persons along rivers and streams in the warned area should take immediate precautions to protect life and property. These forecasts are based on observed precipitation as well as forecast precipitation 24 hours into the future. Changes to the rainfall forecast, or any additional rainfall after 24 hours, may cause changes to these river forecasts. Additional information is available at www.weather.gov. The next statement will be issued by late tonight.
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Frequently Asked Questions
What does a Flood Warning mean for Cook County, Illinois?
Flooding is occurring or imminent along rivers, streams, or low-lying areas.
Is this Flood Warning currently active?
Yes — this alert is active as of our last check (2 minutes ago). It's set to expire August 3, 2026 at 5:30 AM ET.
How do I get notified about Flood Warning alerts for Cook County?
Download StormCast free on Google Play and set Cook County, Illinois as one of your monitored locations. StormCast checks the NWS feed continuously and pushes alerts like this directly to your phone — even with the screen off.