Alert archive / Illinois / Grundy County

Weather alerts in Grundy County, Illinois, 2026

165 weather alerts in 2026, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.

Grundy County and its neighbors

Each county as a circle sized by its count in 2026. Tap one for its archive.

Alerts: 165
Warnings: 40
Watches: 39
Advisories: 40
Busiest month: August42 alerts
Busiest day: August 10, 202614 alerts

Over time

By month

Warning verification

How often warnings here had a storm report inside them, and how much warning the reports had.

3 of 6 tornado warnings covering Grundy County in 2026 had a tornado report inside them; 0 of 2 tornado reports fell inside a warning.

Grundy County, 2026

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
Tornado warnings	6	3	50%	2	0%
Severe thunderstorm warnings	22	14	36%	22	86%	27 min
Flash flood warnings	3	2	33%	1	100%	113 min

Each office's whole area, 2026

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
NWS Chicago, IL: tornado warnings	75	29	61%	91	69%	19 min
NWS Chicago, IL: severe thunderstorm warnings	265	167	37%	1,194	90%	30 min
NWS Chicago, IL: flash flood warnings	59	31	47%	188	86%	119 min

An office's figures cover every county it serves, including across state lines.

The year is still running; reports filed late and damage surveys can still change these figures.

Verified by the Iowa Environmental Mesonet's Cow, which matches each storm-based warning with the local storm reports inside its polygon while it was in force, within 15 km of its edge: a tornado warning counts as verified on a tornado report, a severe thunderstorm warning on hail of 1 inch or more, a gust of 58 mph or more, or wind damage, a flash flood warning on a flash flood report. The false alarm ratio is the share of warnings with no such report; "inside a warning" is the probability of detection, the share of reports that fell inside one; lead time runs from the warning's issue to each report inside it, counting zero for a report that came first. A warning with no report is not proof nothing happened: reports come from spotters, the public and damage surveys, and are thin where few people live.

The alerts

Every alert, in the order issued. Times are local, Central Time. Each opens its own page with the text, the map, the radar and the sounding.

Issued	Product	Office	Lasted
Jan 8, 7:46 PM CST	Areal Flood Advisory	LOT	3 hr
Jan 8, 7:50 PM CST	Mesoscale Discussion	SPC	55 min
Jan 14, 7:46 AM CST	Special Weather Statement	LOT	44 min
Jan 18, 2:13 AM CST	Cold Weather Advisory	LOT	34 hr
Jan 21, 3:01 AM CST	Extreme Cold Watch	LOT	24 hr
Jan 21, 4:42 PM CST	Wind Advisory	LOT	7 hr
Jan 22, 3:12 AM CST	Cold Weather Advisory	LOT	55 hr
Jan 22, 3:12 AM CST	Extreme Cold Warning	LOT	33 hr
Jan 24, 1:51 AM CST	Winter Weather Advisory	LOT	42 hr
Jan 25, 2:35 AM CST	Cold Weather Advisory	LOT	32 hr
Feb 15, 7:24 AM CST	Dense Fog Advisory	LOT	3 hr
Feb 16, 5:20 AM CST	Dense Fog Advisory	LOT	4 hr
Feb 17, 1:45 PM CST	Fire Weather Watch	LOT	11 hr
Feb 18, 1:00 AM CST	Red Flag Warning	LOT	17 hr
Feb 19, 1:56 PM CST	Wind Advisory	LOT	26 hr
Feb 27, 5:58 AM CST	Dense Fog Advisory	LOT	2 hr
Mar 4, 8:34 PM CST	Dense Fog Advisory	LOT	37 hr
Mar 6, 2:10 PM CST	Mesoscale Discussion	SPC	2 hr
Mar 6, 5:02 PM CST	Severe Thunderstorm Watch	SPC	4 hr
Mar 10, 11:16 AM CDT	Mesoscale Discussion	SPC	29 min
Mar 10, 12:04 PM CDT	Flood Watch	LOT	13 hr
Mar 10, 1:53 PM CDT	Mesoscale Discussion	SPC	3 hr
Mar 10, 3:57 PM CDT	Tornado Watch	SPC	10 hr
Mar 10, 4:32 PM CDT	Severe Thunderstorm Warning	LOT	43 min
Mar 10, 7:21 PM CDT	Mesoscale Discussion	SPC	84 min
Mar 10, 7:51 PM CDT	Mesoscale Discussion	SPC	54 min
Mar 10, 7:57 PM CDT	Severe Thunderstorm Warning	LOT	63 min
Mar 12, 1:33 AM CDT	Wind Advisory	LOT	40 hr
Mar 12, 11:28 AM CDT	High Wind Warning	LOT	29 hr
Mar 14, 11:57 AM CDT	Wind Advisory	LOT	30 hr
Mar 15, 9:27 AM CDT	Winter Weather Advisory	LOT	39 hr
Mar 26, 2:48 PM CDT	Mesoscale Discussion	SPC	117 min
Mar 26, 4:15 PM CDT	Severe Thunderstorm Watch	SPC	8 hr
Mar 30, 9:21 PM CDT	Severe Thunderstorm Watch	SPC	6 hr
Mar 31, 1:54 AM CDT	Mesoscale Discussion	SPC	96 min
Mar 31, 7:46 AM CDT	Mesoscale Discussion	SPC	89 min
Mar 31, 9:09 AM CDT	Severe Thunderstorm Warning	LOT	52 min
Mar 31, 9:25 AM CDT	Severe Thunderstorm Watch	SPC	6 hr
Apr 2, 1:32 AM CDT	Wind Advisory	LOT	17 hr
Apr 2, 1:43 PM CDT	Tornado Watch	SPC	8 hr
Apr 2, 7:30 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	45 min
Apr 2, 7:43 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	62 min
Apr 2, 10:13 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	47 min
Apr 2, 10:20 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	25 min
Apr 2, 10:52 PM CDT	Severe Thunderstorm Warning	LOT	68 min
Apr 3, 3:56 PM CDT	Flood Watch	LOT	18 hr
Apr 3, 4:59 PM CDT	Mesoscale Discussion	SPC	2 hr
Apr 3, 9:46 PM CDT	Flash Flood Warning	LOT	4 hr
Apr 4, 1:59 AM CDT	Areal Flood Warning	LOT	8 hr
Apr 13, 2:06 PM CDT	Mesoscale Discussion	SPC	24 min
Apr 14, 1:55 PM CDT	Mesoscale Discussion	SPC	2 hr
Apr 14, 7:11 PM CDT	Flood Watch	LOT	30 hr
Apr 17, 11:48 AM CDT	Flood Watch	LOT	15 hr
Apr 17, 3:31 PM CDT	Tornado Watch	SPC	8 hr
Apr 17, 8:09 PM CDT	Mesoscale Discussion	SPC	2 hr
Apr 17, 8:47 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	73 min
Apr 17, 9:23 PM CDT	Tornado Warning	LOT	52 min
Apr 18, 1:29 PM CDT	Frost Advisory	LOT	20 hr
Apr 18, 1:29 PM CDT	Freeze Watch	LOT	12 hr
Apr 19, 1:52 AM CDT	Freeze Warning	LOT	30 hr
Apr 21, 1:07 PM CDT	Mesoscale Discussion	SPC	113 min
Apr 27, 11:18 AM CDT	Wind Advisory	LOT	5 hr
May 1, 3:32 AM CDT	Frost Advisory	LOT	28 hr
May 4, 2:59 AM CDT	Blowing Dust Advisory	LOT	15 hr
May 4, 3:42 PM CDT	Mesoscale Discussion	SPC	2 hr
May 4, 7:13 PM CDT	Severe Thunderstorm Warning	LOT	34 min
May 6, 1:23 PM CDT	Frost Advisory	LOT	19 hr
May 12, 9:36 AM CDT	Blowing Dust Advisory	LOT	9 hr
May 18, 8:40 AM CDT	Mesoscale Discussion	SPC	2 hr
May 18, 10:02 AM CDT	Severe Thunderstorm Watch	SPC	7 hr
May 18, 10:13 AM CDT	Severe Thunderstorm Warning	LOT	37 min
Jun 6, 5:39 AM CDT	Mesoscale Discussion	SPC	2 hr
Jun 7, 4:31 PM CDT	Areal Flood Advisory	LOT	3 hr
Jun 8, 12:58 PM CDT	Mesoscale Discussion	SPC	92 min
Jun 10, 2:06 PM CDT	Mesoscale Discussion	SPC	54 min
Jun 10, 2:40 PM CDT	Severe Thunderstorm Watch	SPC	4 hr
Jun 10, 3:04 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	71 min
Jun 10, 3:22 PM CDT	Tornado Warning	LOT	23 min
Jun 10, 3:58 PM CDT	Mesoscale Discussion	SPC	2 hr
Jun 10, 6:35 PM CDT	Mesoscale Discussion	SPC	55 min
Jun 10, 6:54 PM CDT	Flood Watch	LOT	7 hr
Jun 10, 7:06 PM CDT	Tornado Watch	SPC	4 hr
Jun 10, 7:55 PM CDT	Mesoscale Discussion	SPC	95 min
Jun 11, 10:05 AM CDT	Flood Watch	LOT	11 hr
Jun 11, 12:22 PM CDT	Mesoscale Discussion	SPC	83 min
Jun 11, 1:57 PM CDT	Tornado Watch	SPC	7 hr
Jun 11, 3:00 PM CDT	High Wind Warning	LOT	60 min
Jun 11, 5:13 PM CDT	Mesoscale Discussion	SPC	62 min
Jun 11, 5:55 PM CDT	Tornado Warning Tornado observedConsiderable damage threat	LOT	37 min
Jun 11, 6:07 PM CDT	Tornado Warning Tornado observed	LOT	38 min
Jun 11, 6:14 PM CDT	Mesoscale Discussion	SPC	91 min
Jun 11, 6:17 PM CDT	Severe Thunderstorm Warning	LOT	28 min
Jun 17, 2:20 AM CDT	Flood Watch	LOT	15 hr
Jun 17, 7:49 AM CDT	Tornado Watch	SPC	6 hr
Jun 24, 12:44 PM CDT	Mesoscale Discussion	SPC	3 hr
Jun 24, 1:55 PM CDT	Severe Thunderstorm Watch	SPC	8 hr
Jun 24, 7:19 PM CDT	Severe Thunderstorm Warning	LOT	56 min
Jun 24, 8:06 PM CDT	Areal Flood Advisory	LOT	3 hr
Jun 24, 8:06 PM CDT	Mesoscale Discussion	SPC	84 min
Jun 28, 2:47 AM CDT	Heat Advisory	LOT	47 hr
Jun 28, 11:18 AM CDT	Extreme Heat Warning	LOT	5 days
Jul 2, 11:43 PM CDT	Mesoscale Discussion	SPC	2 hr
Jul 3, 11:15 AM CDT	Mesoscale Discussion	SPC	2 hr
Jul 3, 11:52 AM CDT	Severe Thunderstorm Watch	SPC	6 hr
Jul 3, 2:02 PM CDT	Severe Thunderstorm Warning	LOT	43 min
Jul 3, 5:05 PM CDT	Mesoscale Discussion	SPC	115 min
Jul 3, 6:37 PM CDT	Severe Thunderstorm Watch	SPC	6 hr
Jul 3, 8:32 PM CDT	Flood Watch	LOT	4 hr
Jul 3, 8:33 PM CDT	Mesoscale Discussion	SPC	117 min
Jul 4, 9:39 AM CDT	Flood Watch	LOT	10 hr
Jul 4, 11:24 AM CDT	Mesoscale Discussion	SPC	3 hr
Jul 4, 12:33 PM CDT	Severe Thunderstorm Watch	SPC	6 hr
Jul 4, 3:19 PM CDT	Severe Thunderstorm Warning	LOT	56 min
Jul 4, 3:51 PM CDT	Mesoscale Discussion	SPC	84 min
Jul 4, 4:45 PM CDT	Areal Flood Advisory	LOT	2 hr
Jul 18, 11:37 AM CDT	Mesoscale Discussion	SPC	113 min
Jul 27, 2:10 AM CDT	Extreme Heat Warning	LOT	19 hr
Jul 27, 3:02 AM CDT	Dense Fog Advisory	LOT	5 hr
Jul 27, 3:26 PM CDT	Severe Thunderstorm Warning	LOT	64 min
Jul 27, 3:48 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	57 min
Aug 1, 4:20 AM CDT	Areal Flood Advisory	LOT	6 hr
Aug 1, 10:22 AM CDT	Flood Watch	LOT	11 hr
Aug 1, 2:16 PM CDT	Areal Flood Advisory	LOT	5 hr
Aug 7, 2:46 AM CDT	Dense Fog Advisory	LOT	6 hr
Aug 9, 5:03 PM CDT	Flood Watch	LOT	10 hr
Aug 9, 8:14 PM CDT	Mesoscale Discussion	SPC	2 hr
Aug 9, 8:43 PM CDT	Severe Thunderstorm Watch	SPC	7 hr
Aug 9, 10:53 PM CDT	Mesoscale Discussion	SPC	2 hr
Aug 9, 11:23 PM CDT	Areal Flood Advisory	LOT	3 hr
Aug 9, 11:35 PM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	70 min
Aug 9, 11:47 PM CDT	Flash Flood Warning	LOT	3 hr
Aug 9, 11:59 PM CDT	Tornado Warning Tornado observed	LOT	17 min
Aug 10, 12:36 AM CDT	Severe Thunderstorm Warning	LOT	69 min
Aug 10, 1:05 AM CDT	Areal Flood Advisory	LOT	8 hr
Aug 10, 2:32 AM CDT	Areal Flood Warning	LOT	3 hr
Aug 10, 2:48 AM CDT	Areal Flood Advisory	LOT	7 hr
Aug 10, 12:47 PM CDT	Mesoscale Discussion	SPC	2 hr
Aug 10, 5:15 PM CDT	Mesoscale Discussion	SPC	2 hr
Aug 10, 6:21 PM CDT	Severe Thunderstorm Watch	SPC	7 hr
Aug 11, 7:22 AM CDT	Severe Thunderstorm Watch	SPC	6 hr
Aug 11, 9:00 AM CDT	Mesoscale Discussion	SPC	2 hr
Aug 11, 9:48 AM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	72 min
Aug 11, 9:59 AM CDT	Areal Flood Advisory	LOT	4 hr
Aug 11, 10:27 AM CDT	Tornado Warning	LOT	37 min
Aug 11, 8:04 PM CDT	Mesoscale Discussion	SPC	2 hr
Aug 12, 6:41 AM CDT	Severe Thunderstorm Watch	SPC	6 hr
Aug 12, 9:03 AM CDT	Severe Thunderstorm Warning Considerable damage threat	LOT	46 min
Aug 12, 9:04 AM CDT	Mesoscale Discussion	SPC	116 min
Aug 12, 9:06 AM CDT	Areal Flood Advisory	LOT	3 hr
Aug 12, 9:37 AM CDT	Flash Flood Warning	LOT	3 hr
Aug 12, 12:17 PM CDT	Areal Flood Advisory	LOT	118 min
Aug 13, 2:08 AM CDT	Flood Watch	LOT	32 hr
Aug 13, 2:42 AM CDT	Dense Fog Advisory	LOT	6 hr
Aug 13, 11:03 PM CDT	Mesoscale Discussion	SPC	117 min
Aug 13, 11:35 PM CDT	Areal Flood Advisory	LOT	3 hr
Aug 14, 12:01 PM CDT	Flood Watch	LOT	22 hr
Aug 15, 6:39 PM CDT	Flood Watch	LOT	13 hr
Aug 19, 4:52 PM CDT	Mesoscale Discussion	SPC	83 min
Aug 21, 2:22 PM CDT	Mesoscale Discussion	SPC	113 min
Aug 21, 2:57 PM CDT	Severe Thunderstorm Watch	SPC	9 hr
Aug 31, 12:24 PM CDT	Heat Advisory	LOT	33 hr
Aug 31, 12:24 PM CDT	Heat Advisory	LOT	3 days
Sep 3, 7:56 PM CDT	Heat Advisory	LOT	25 hr
Sep 15, 2:35 PM CDT	Mesoscale Discussion	SPC	115 min
Sep 18, 1:47 PM CDT	Flood Watch	LOT	47 hr

By product

Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.

Product	Alerts
Severe storms
Severe Thunderstorm Warning	22
Tornado Warning	6
Severe Thunderstorm Watch	15
Tornado Watch	6
Mesoscale Discussion	45
Special Weather Statement	1
Flooding
Areal Flood Warning	2
Flash Flood Warning	3
Flood Watch	15
Areal Flood Advisory	13
Winter
Winter Weather Advisory	2
Heat
Extreme Heat Warning	2
Heat Advisory	4
Cold
Extreme Cold Warning	1
Freeze Warning	1
Extreme Cold Watch	1
Freeze Watch	1
Cold Weather Advisory	3
Frost Advisory	3
Wind and dust
High Wind Warning	2
Blowing Dust Advisory	2
Wind Advisory	6
Fire
Red Flag Warning	1
Fire Weather Watch	1
Fog and smoke
Dense Fog Advisory	7

The busiest days

Days with the most alerts issued, by UTC date.

Nearby

Alerts in force now Tornadoes on record Forecast The radar archive 2025

Sources

National Weather Service watches, warnings, advisories and statements from the Iowa Environmental Mesonet's VTEC archive, which reconstructs tornado, severe thunderstorm, flash flood and marine warnings back to 1986 from the NWS text archive. Storm Prediction Center watches and mesoscale discussions from SPC's archive through the Mesonet. County centers from the US Census Bureau. Warning verification from the Mesonet's Cow. Rebuilt daily.