NWS Chicago ILFF.W 0057September 17, 2026
Flash Flood Warning: De Kalb, La Salle and Lee, IL
The National Weather Service office in Chicago issued a flash flood warning for De Kalb, La Salle and Lee in Illinois, which was in force until 11:00 a.m. local time on September 17. It was the 57th flash flood warning the NWS office in Chicago issued in 2026. Illinois had 5 flash flood warnings in September 2026, against 9 in an average September of 2008-2025 (Illinois's flash flood warnings by year).
ExpiredWarning
In force for 3.9 hours; it has expired. The agency may have replaced it with a new notice.
The notice
- Issued by
- National Weather Service, Chicago IL
- Area
- De Kalb, La Salle and Lee
- State
- Illinois
- Level
- Warning
- Issued
- 7:07 a.m. CDT, September 17, 2026
- Expires
- 11:00 a.m. CDT, September 17, 2026
- CAP severity, certainty, urgency
- Severe, Likely, Immediate
- VTEC event
- KLOT FF.W 0057
- Official source
- National Weather Service: the notice at its source
Source: National Weather Service: the notice at its source. AreaZine rebuilds this page from the agency's record; the agency's page is the one to act on. A U.S. Government work, in the public domain.
The notice as issued
FFWLOT The National Weather Service in Chicago has issued a * Flash Flood Warning for... Southern De Kalb County in north central Illinois... Northern La Salle County in north central Illinois... Southeastern Lee County in north central Illinois... * Until 1100 AM CDT. * At 707 AM CDT, Doppler radar and automated rain gauges indicated thunderstorms producing heavy rain across the warned area. Between 2 and 4 inches of rain have fallen. Additional rainfall amounts up to 1 inch are possible in the warned area. Flash flooding is ongoing or expected to begin shortly. HAZARD...Flash flooding caused by thunderstorms. SOURCE...Radar and automated gauges. IMPACT...Rapid-onset flooding of creeks, streams, drainage ditches, streets, underpasses, low-lying areas, and other poor drainage areas. * Some locations that will experience flash flooding include... Sandwich, Mendota, Amboy, Sheridan, Lake Holiday, Somonauk, Earlville, Leland, Paw Paw, Sublette, Woodhaven Lakes, Millington, Compton and West Brooklyn.
What the agency told people to do
A Flash Flood Warning means rapid-onset flooding is imminent or may already be occurring. Persons along creeks, drainage ditches, and other waterways should take immediate precautions to protect life and property.
Source: National Weather Service: the notice at its source. The text is the agency's, unedited. A U.S. Government work, in the public domain.