Alert archive / Illinois / Flash Flood Warnings in 2026

Flash Flood Warning 17, NWS Chicago, IL

June 17, 2026Cook County, Illinois; Lake County, Indiana

NWS Chicago, IL issued this flash flood warning at Jun 17, 2026, 3:55 PM CDT for Cook County, Illinois; Lake County, Indiana. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Jun 17, 2026, 3:55 PM CDT (20:55 UTC)
Expired: Jun 17, 2026, 7:00 PM CDT
In force: 3 hr
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Flood severity: None

Counties Cook County, IL, Lake County, IN

The radar

The Chicago radar (KLOT), 48 km from the middle of the area, began a volume at 20:57 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 forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Chicago, IL wrote its last area forecast discussion before this flash flood warning went out at Jun 17, 2:11 PM CDT, 1 hour 44 minutes earlier.

Area forecast discussion, Jun 17, 2:11 PM CDT, 1 hour 44 minutes before

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Hazardous weather outlook, Jun 17, 2:19 PM CDT, 1 hour 36 minutes before

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
219 PM CDT Wed Jun 17 2026

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-181930-
Winnebago-Boone-McHenry-Lake IL-Ogle-Lee-De Kalb-Kane-DuPage-
La Salle-Kendall-Grundy-Kankakee-Livingston-Iroquois-Ford-
Northern Cook-Central Cook-Southern Cook-Northern Will-
Southern Will-Eastern Will-Lake IN-Porter-Newton-Jasper-Benton-
219 PM CDT Wed Jun 17 2026 /319 PM EDT Wed Jun 17 2026/

This Hazardous Weather Outlook is for portions of north central
Illinois...northeast Illinois and northwest Indiana.

.DAY ONE...Tonight.

Weather hazards expected...

  Significant Thunderstorm Risk...with an associated:
     Level 3 of 5 Tornado Risk mainly south of the Kankakee River.
     Level 3 of 5 Damaging Wind Risk...up to 65 mph.
     Level 3 of 5 Large Hail Risk...up to half dollar size.
  Significant Flooding Risk mainly near and south of I-80.
  High Swim Risk Illinois Lake Michigan Beaches.

DISCUSSION...

Thunderstorms are expected this afternoon and early evening. The
strongest storms, currently favored south of the Kankakee River,
will be capable of producing large hail, damaging winds, and
potentially strong tornadoes. Farther north, damaging winds will
be the biggest concern with afternoon storms.

Thunderstorms today will also be capable of producing torrential
rainfall which could lead to localized flash flooding and sudden
river/stream rises.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Thursday...
  High Swim Risk Porter County Lake Michigan Beaches.
Saturday...
  Limited Thunderstorm Risk.
Sunday...
  Limited Flooding Risk.
  Limited Thunderstorm Risk.
Monday and Tuesday...
  Limited Thunderstorm Risk.

.SPOTTER INFORMATION STATEMENT...

  Spotters will likely be needed this afternoon and evening.

GENERAL STORM MOTION OF THE DAY:

  Moving toward the east at 50 to 60 mph.

LMZ740>745-181930-
Winthrop Harbor to Wilmette Harbor IL-
Wilmette Harbor to Northerly Island IL-
Northerly Island to Calumet Harbor IL-
Calumet Harbor IL to Gary IN-Gary to Burns Harbor IN-
Burns Harbor to Michigan City IN-
219 PM CDT Wed Jun 17 2026

This Hazardous Weather Outlook is for portions of the Illinois
nearshore waters of Lake Michigan and the Indiana nearshore
waters of Lake Michigan.

.DAY ONE...Tonight.

Weather hazards expected...

  Gale force winds and or very hazardous waves.
  Significant Thunderstorm Risk...with an associated:
     Thunderstorm Waterspout Risk
     Level 3 of 5 Thunderstorm Wind Gust Risk...up to 50 knots.
     Level 2 of 5 Hail Risk...up to quarter size.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Thursday morning...
  Hazardous conditions for small craft are likely.
Saturday...
  Limited Thunderstorm Risk.
Sunday...
  Hazardous conditions for small craft are likely.
  Limited Thunderstorm Risk.
Monday...
  Hazardous conditions for small craft are likely.
Tuesday...
  Limited Thunderstorm Risk.

Doom

Visit us at www.weather.gov/chicago

In the hours before

Local storm report, Jun 17, 12:22 PM CDT, 3 hours 33 minutes before

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Local storm report, Jun 17, 12:24 PM CDT, 3 hours 31 minutes before

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Local storm report, Jun 17, 12:47 PM CDT, 3 hours 8 minutes before

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Local storm report, Jun 17, 12:48 PM CDT, 3 hours 7 minutes before

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Local storm report, Jun 17, 12:50 PM CDT, 3 hours 5 minutes before

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Local storm report, Jun 17, 12:52 PM CDT, 3 hours 3 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 16, 9:51 PM CDT	Small Craft Advisory	LOT		16 hr
Jun 17, 2:20 AM CDT	Flood Watch	LOT	Boone, Cook, DeKalb, DuPage, Ford, Grundy and 12 more	15 hr
Jun 17, 9:17 AM CDT	Wind Advisory	LOT	Boone, Cook, DeKalb, DuPage, Kane, Lake and 4 more	5 hr
Jun 17, 10:02 AM CDT	Severe Thunderstorm Warning	LOT	Livingston	58 min
Jun 17, 10:29 AM CDT	Special Marine Warning	LOT		3 hr
Jun 17, 1:26 PM CDT	Gale Warning	LOT		110 min
Jun 17, 1:26 PM CDT	Small Craft Advisory	LOT		20 hr
Jun 17, 3:10 PM CDT	Areal Flood Advisory	LOT	Cook, Will	2 hr
Jun 17, 4:47 PM CDT	River Flood Warning	LOT	Cook	11 hr
Jun 17, 6:06 PM CDT	River Flood Warning	LOT	Cook	27 hr
Jun 17, 4:00 PM CDT	Areal Flood Advisory	LOT	Porter	3 hr

Nearby

Flash Flood Warnings in Illinois, 2026 Flash Flood Warnings in Indiana, 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; radar from the NEXRAD Level II archive.