Alert archive / Illinois / Severe Thunderstorm Warnings in 2025

Severe Thunderstorm Warning 113, NWS Chicago, IL

August 16, 2025DeKalb County, Lee County, Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Aug 16, 2025, 7:43 PM CDT for DeKalb County, Lee County, Illinois. It was in force for 16 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 16, 2025, 7:43 PM CDT (00:43 UTC)
Expired: Aug 16, 2025, 7:59 PM CDT
In force: 16 min
Issued by: NWS Chicago, IL
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties DeKalb County, IL, Lee County, IL

The radar

The Chicago radar (KLOT), 82 km from the middle of the area, began a volume at 00:44 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.

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 0.7 hours before the alert went out and 124 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: 3449 J/kg
Mixed-layer CIN: -35 J/kg
Mixed-layer LCL: 1352 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 108 m²/s²
0-3 km storm-relative helicity: 93 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 5.3

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm 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 severe thunderstorm warning went out at Aug 16, 6:50 PM CDT, 53 minutes earlier.

Area forecast discussion, Aug 16, 6:50 PM CDT, 53 minutes before

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Hazardous weather outlook, Aug 16, 3:45 PM CDT, 3 hours 58 minutes before

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
345 PM CDT Sat Aug 16 2025

ILZ003>006-008-010>013-019>021-023-032-033-039-103>108-INZ001-002-
010-011-019-172045-
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-
345 PM CDT Sat Aug 16 2025 /445 PM EDT Sat Aug 16 2025/

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 2 of 5 Damaging Wind Risk...up to 70 mph.
     Level 2 of 5 Large Hail Risk...up to 1 inch in diameter.
  Elevated Flooding Risk.
  Elevated Excessive Heat Risk through early evening south of I-80.

DISCUSSION...

Clusters of thunderstorms will move across the area into this
evening. Damaging winds will be the primary threat, which may
locally exceed 70 mph, though some instances of large hail are
also possible. Additional thunderstorms may develop into tonight
with a threat for flash flooding.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Sunday...
  High swim risk developing Lake Michigan Beaches.
  Limited Thunderstorm Risk.
  Limited Excessive Heat Risk.
Monday...
Limited Flooding Risk.
  Limited Thunderstorm Risk...with an associated:
     Level 1 of 5 Severe Thunderstorm Risk.
  Elevated Excessive Heat Risk.
Tuesday...
  Limited Flooding Risk.
  Limited Thunderstorm Risk.

.SPOTTER INFORMATION STATEMENT...

  Spotters may be needed into this evening.

GENERAL STORM MOTION OF THE DAY:

  Moving toward the south at 35 to 40 mph.

LMZ740>745-172045-
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-
345 PM CDT Sat Aug 16 2025

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...

  Significant Thunderstorm Risk...with an associated:
     Level 1 of 5 Thunderstorm Wind Gust Risk...up to 60 knots.
     Level 2 of 5 Hail Risk...up to Quarter size.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Sunday...
  Hazardous conditions for small craft are likely.
  Limited Thunderstorm Risk.
Monday...
  Limited Thunderstorm Risk...with an associated:
     Level 1 of 5 Severe Thunderstorm Risk.
Tuesday...
  Limited Thunderstorm Risk.
Tuesday night and Wednesday...
  Hazardous conditions for small craft are likely.

KJB

Visit us at www.weather.gov/chicago

In the hours before

Local storm report, Aug 16, 6:44 PM CDT, 59 minutes before

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Local storm report, Aug 16, 6:53 PM CDT, 50 minutes before

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Local storm report, Aug 16, 7:01 PM CDT, 42 minutes before

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Special weather statement, Aug 16, 7:18 PM CDT, 25 minutes before

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Local storm report, Aug 16, 7:35 PM CDT, 8 minutes before

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Local storm report, Aug 16, 7:42 PM CDT, 1 minute 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
Aug 16, 7:09 PM CDT	Severe Thunderstorm Warning	LOT	DeKalb, Lee, Ogle	35 min
Aug 16, 7:17 PM CDT	Special Marine Warning	LOT		118 min
Aug 16, 7:18 PM CDT	Special Weather Statement	LOT	Cook	27 min
Aug 16, 8:34 PM CDT	Special Weather Statement	LOT	Ford	26 min
Aug 16, 8:40 PM CDT	Severe Thunderstorm Warning	LOT	Ford, Iroquois, Livingston	35 min
Aug 16, 8:42 PM CDT	Special Weather Statement	LOT	Kankakee	18 min
Aug 16, 8:57 PM CDT	Special Weather Statement	LOT	Livingston	18 min
Aug 16, 9:05 PM CDT	Areal Flood Advisory	LOT	Ford, Iroquois, Livingston	3 hr
Aug 16, 9:19 PM CDT	Special Weather Statement	LOT	Ford	26 min
Aug 16, 9:23 PM CDT	Special Weather Statement	LOT	Livingston	22 min
Aug 16, 9:56 PM CDT	Areal Flood Advisory	LOT	Ford, Iroquois, Livingston	4 hr
Aug 16, 10:12 PM CDT	Special Weather Statement	LOT	Ford	18 min
Aug 16, 11:15 PM CDT	Special Weather Statement	LOT	Lake	15 min
Aug 16, 11:19 PM CDT	Special Marine Warning	LOT		56 min
Aug 16, 11:27 PM CDT	Special Weather Statement	LOT	Lake	18 min
Aug 16, 11:59 PM CDT	Special Marine Warning	LOT		91 min
Aug 17, 12:54 AM CDT	Areal Flood Advisory	LOT	Cook	3 hr
Aug 17, 1:21 AM CDT	Areal Flood Advisory	LOT	Cook	3 hr
Aug 17, 1:41 AM CDT	Areal Flood Advisory	LOT	Cook, DuPage, Kane, Lake, McHenry	2 hr
Aug 17, 1:46 AM CDT	Special Weather Statement	LOT	McHenry	29 min
Aug 17, 2:04 AM CDT	Areal Flood Advisory	LOT	Kankakee, Will	3 hr
Aug 17, 2:11 AM CDT	Special Weather Statement	LOT	Cook	34 min
Aug 17, 2:17 AM CDT	Special Marine Warning	LOT		65 min
Aug 17, 2:27 AM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage	48 min
Aug 17, 2:32 AM CDT	Flash Flood Warning	LOT	Cook, DuPage	118 min
Aug 17, 2:48 AM CDT	Severe Thunderstorm Warning	LOT	Cook, DuPage, Will	27 min
Aug 17, 2:59 AM CDT	Severe Thunderstorm Warning	LOT	Cook, Will	46 min
Aug 17, 3:14 AM CDT	Areal Flood Advisory	LOT	Boone, Cook, DeKalb, DuPage, Kane, Kankakee and 2 more	3 hr
Aug 17, 3:16 AM CDT	Special Weather Statement	LOT	Will	29 min
Aug 17, 3:28 AM CDT	Severe Thunderstorm Warning	LOT	Kankakee, Will	47 min
Aug 17, 3:36 AM CDT	Flash Flood Warning	LOT	Cook, DuPage, Kane, Kendall, Will	114 min
Aug 17, 3:51 AM CDT	Special Weather Statement	LOT	Kankakee	24 min
Aug 17, 4:13 AM CDT	Flash Flood Warning Considerable damage threat	LOT	Kane, Kendall, Will	2 hr
Aug 17, 4:20 AM CDT	Flash Flood Warning	LOT	Grundy, Iroquois, Kankakee, Kendall, Will	3 hr
Aug 17, 4:30 AM CDT	Areal Flood Advisory	LOT	Cook, DuPage	3 hr
Aug 17, 5:16 AM CDT	Beach Hazards Statement	LOT	Cook, Lake	34 hr
Aug 17, 5:16 AM CDT	Small Craft Advisory	LOT		29 hr
Aug 17, 5:22 AM CDT	Areal Flood Advisory	LOT	Ford, Grundy, Iroquois, Kankakee, LaSalle, Livingston	113 min
Aug 17, 5:32 AM CDT	Areal Flood Advisory	LOT	Cook, DuPage, Kane, Kendall, Will	6 hr
Aug 17, 6:07 AM CDT	Areal Flood Advisory	LOT	Ford, LaSalle, Livingston	113 min
Aug 17, 6:14 AM CDT	Areal Flood Warning	LOT	Kane, Kendall, Will	6 hr
Aug 17, 6:28 AM CDT	Special Weather Statement	LOT	Kendall, Will	32 min
Aug 17, 7:11 AM CDT	Areal Flood Advisory	LOT	Grundy, Iroquois, Kankakee, Kendall, Will	3 hr
Aug 17, 7:35 AM CDT	Special Weather Statement	LOT	Grundy	25 min
Aug 17, 9:47 AM CDT	River Flood Warning	LOT	Will	11 hr
Aug 17, 6:57 PM CDT	Areal Flood Advisory	LOT	LaSalle	2 hr
Aug 16, 7:24 PM CDT	Areal Flood Advisory	LOT	Jasper	111 min
Aug 17, 4:02 AM CDT	Special Weather Statement	LOT	Newton	28 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2025 Every severe thunderstorm warning in 2025

Sources

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