Alert archive / Illinois / Flash Flood Warnings in 2026

Flash Flood Warning 21, NWS Chicago, IL

July 3, 2026DeKalb County, Kane County, Kendall County, Illinois

NWS Chicago, IL issued this flash flood warning at Jul 3, 2026, 12:16 AM CDT for DeKalb County, Kane County, Kendall County, Illinois. It was in force for 114 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jul 3, 2026, 12:16 AM CDT (05:16 UTC)
Expired: Jul 3, 2026, 2:10 AM CDT
In force: 114 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Flood severity: None

Counties DeKalb County, IL, Kane County, IL, Kendall County, IL

The radar

The Chicago radar (KLOT), 48 km from the middle of the area, began a volume at 05:16 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

Time	Report	Where	Remark
Jul 3, 1:00 AM CDT	RAIN 4.28	3 Wnw North Aurora, IL	3.7 WNW North Aurora, IL. Measured on Davis Weatherlink Station.
Jul 3, 2:06 AM CDT	FLASH FLOOD	1 E Sandwich, IL	Several low lying areas of Sandwich were flooded. A picture shared showed several inches of standing water at Griswold Springs Rd just east of Duvick Ave.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 5.3 hours before the alert went out and 154 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 1944 J/kg
Mixed-layer CIN: -14 J/kg
Mixed-layer LCL: 1423 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 62 m²/s²
0-3 km storm-relative helicity: 104 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 4.1

Open this sounding in Storm Lab

The text

As transmitted.

886 
WGUS53 KLOT 030516
FFWLOT
ILC037-089-093-030815-
/O.NEW.KLOT.FF.W.0021.260703T0516Z-260703T0815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Chicago IL
1216 AM CDT Fri Jul 3 2026

The National Weather Service in Chicago has issued a

* Flash Flood Warning for...
  Southeastern De Kalb County in north central Illinois...
  Southern Kane County in northeastern Illinois...
  Northwestern Kendall County in northeastern Illinois...

* Until 315 AM CDT.

* At 1216 AM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Additional rainfall amounts of 1 to 2 inches are 
  possible in the warned area. Flash flooding is ongoing or expected 
  to begin shortly.

  HAZARD...Flash flooding.

  SOURCE...Radar.

  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...
  Aurora, St. Charles, Batavia, Geneva, Plano, Sandwich, North 
  Aurora, Sugar Grove, Elburn, Hinckley, Somonauk, Waterman, Big 
  Rock, Kaneville and Little Rock.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

LAT...LON 4184 8861 4191 8832 4183 8830 4173 8852
      4164 8852 4163 8868 4163 8869 4163 8871
      4163 8880 4163 8881 4163 8882 4166 8882
      4178 8882

FLASH FLOOD...RADAR INDICATED

$$

DK

1 follow-up statement

012 
WGUS73 KLOT 030710 RRA
FFSLOT

Flash Flood Statement
National Weather Service Chicago IL
210 AM CDT Fri Jul 3 2026

ILC037-089-093-030720-
/O.CAN.KLOT.FF.W.0021.000000T0000Z-260703T0815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
De Kalb IL-Kane IL-Kendall IL-
210 AM CDT Fri Jul 3 2026

...FLASH FLOOD WARNING IS CANCELLED FOR SOUTHEASTERN DE KALB, 
SOUTHERN KANE AND NORTHWESTERN KENDALL COUNTIES...

The heavy rain has ended. This warning has been replaced by an areal 
flood warning for lingering flooding issues. Please continue to heed 
remaining road closures.

&&

LAT...LON 4184 8861 4191 8832 4183 8830 4173 8852
      4164 8852 4163 8868 4163 8869 4163 8871
      4163 8880 4163 8881 4163 8882 4166 8882
      4178 8882

$$

DK

The office that day

Everything else NWS Chicago, IL issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 2, 8:35 PM CDT	Special Marine Warning	LOT		85 min
Jul 2, 8:58 PM CDT	Areal Flood Advisory	LOT	Cook, DuPage, Lake	3 hr
Jul 2, 9:44 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage	46 min
Jul 2, 10:06 PM CDT	Special Marine Warning	LOT		3 hr
Jul 2, 10:17 PM CDT	Areal Flood Advisory	LOT	Cook, DuPage	3 hr
Jul 2, 10:26 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage	64 min
Jul 2, 10:51 PM CDT	Areal Flood Advisory	LOT	Cook, DuPage, Kane, Kendall, Will	3 hr
Jul 2, 11:15 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb, Kane, Kendall	60 min
Jul 2, 11:17 PM CDT	Flash Flood Warning	LOT	DuPage, Kane, Kendall	3 hr
Jul 3, 12:00 AM CDT	Areal Flood Advisory	LOT	DeKalb, Kane	2 hr
Jul 3, 1:22 AM CDT	Areal Flood Advisory	LOT	Cook, DuPage, Kane, Kendall, Will	7 hr
Jul 3, 1:35 AM CDT	Special Marine Warning	LOT		52 min
Jul 3, 2:04 AM CDT	Areal Flood Warning	LOT	DeKalb, DuPage, Kane, Kendall, Will	6 hr
Jul 3, 7:59 AM CDT	Areal Flood Warning	LOT	Cook, DuPage	10 hr
Jul 3, 8:01 AM CDT	Areal Flood Advisory	LOT	Cook, DuPage, Kane, Kendall, Will	3 hr
Jul 3, 8:59 AM CDT	Heat Advisory	LOT	Ford, Iroquois, Kankakee, Livingston	10 hr
Jul 3, 10:56 AM CDT	Severe Thunderstorm Warning	LOT	Ogle	64 min
Jul 3, 11:14 AM CDT	Severe Thunderstorm Warning	LOT	Boone, Winnebago	61 min
Jul 3, 12:21 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb, LaSalle, Lee	54 min
Jul 3, 12:42 PM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage, Kane	63 min
Jul 3, 12:44 PM CDT	Severe Thunderstorm Warning	LOT	Kendall	46 min
Jul 3, 12:48 PM CDT	Special Marine Warning	LOT		117 min
Jul 3, 1:05 PM CDT	Severe Thunderstorm Warning	LOT	Cook	40 min
Jul 3, 2:02 PM CDT	Severe Thunderstorm Warning	LOT	Grundy, Kendall, Will	43 min
Jul 3, 2:11 PM CDT	Areal Flood Advisory	LOT	Cook	3 hr
Jul 3, 2:27 PM CDT	Severe Thunderstorm Warning	LOT	Cook	48 min
Jul 3, 2:40 PM CDT	Special Marine Warning	LOT		60 min
Jul 3, 2:40 PM CDT	Special Marine Warning	LOT		60 min
Jul 3, 2:40 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	Will	59 min
Jul 3, 4:26 PM CDT	Severe Thunderstorm Warning	LOT	Will	49 min
Jul 3, 6:35 PM CDT	Tornado Warning	LOT	Ogle, Winnebago	25 min
Jul 3, 6:51 PM CDT	Severe Thunderstorm Warning	LOT	Ogle, Winnebago	54 min

Nearby

Flash Flood Warnings in Illinois, 2026 Every flash flood warning in 2026

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.