Severe Thunderstorm Warnings in Calhoun County, Iowa

422 severe thunderstorm warnings since 1986. An alert counts here when it covered this county. The archive of severe thunderstorm warnings reaches back to 1986.

Calhoun County and its neighbors

Each county as a circle sized by its count since 1986. Tap one for its archive.

Severe Thunderstorm Warnings: 422
Busiest year: 201833 severe thunderstorm warnings
Average year: 10over 41 years on file

Over time

By year

Before October 2007 these were issued for whole counties, and a storm crossing three counties was often three warnings; since then one polygon follows the storm. The count changed with the practice, not only with the weather.

Warning verification

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

From 2008 to 2025, 81% of hail, wind and damage reports in Calhoun County fell inside a severe thunderstorm warning issued on average 22 minutes before, and 47% of the severe thunderstorm warnings had no report inside them.

Severe thunderstorm warnings by year

	Warnings	With a report	False alarm ratio	Reports	Inside a warning	Mean lead time
2008	24	13	46%	9	78%	28 min
2009	14	8	43%	9	100%	23 min
2010	24	5	79%	8	50%	33 min
2011	14	8	43%	2	100%	12 min
2012	14	13	7%	9	67%	24 min
2013	7	4	43%	3	33%	1 min
2014	26	13	50%	15	87%	23 min
2015	15	8	47%	9	78%	13 min
2016	12	8	33%	5	80%	18 min
2017	20	13	35%	9	100%	31 min
2018	33	12	64%	9	78%	9 min
2019	6	2	67%	1	100%	3 min
2020	9	6	33%	4	75%	11 min
2021	6	4	33%	1	100%	29 min
2022	14	12	14%	1	100%	10 min
2023	9	6	33%	2	100%	15 min
2024	15	7	53%	3	67%	19 min
2025	28	13	54%	4	100%	34 min

Years from 2008, the first full year of storm-based warnings. The year still running is on its own page.

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 latest severe thunderstorm warnings

The most recent on file, newest first.

Issued	Product	Office	Lasted
Sep 6, 4:13 PM CDT	Severe Thunderstorm Warning	DMX	47 min
Sep 6, 3:47 PM CDT	Severe Thunderstorm Warning	DMX	43 min
Jul 8, 6:33 PM CDT	Severe Thunderstorm Warning	DMX	42 min
Jul 8, 6:02 PM CDT	Severe Thunderstorm Warning	DMX	43 min
Jul 2, 5:10 PM CDT	Severe Thunderstorm Warning	DMX	50 min
Jul 2, 4:03 PM CDT	Severe Thunderstorm Warning	DMX	43 min
Jun 17, 4:31 AM CDT	Severe Thunderstorm Warning	DMX	44 min
Jun 17, 3:53 AM CDT	Severe Thunderstorm Warning	DMX	52 min
May 17, 9:42 PM CDT	Severe Thunderstorm Warning	DMX	63 min
May 17, 9:26 PM CDT	Severe Thunderstorm Warning	DMX	79 min
May 17, 9:02 PM CDT	Severe Thunderstorm Warning Considerable damage threat	DMX	43 min
May 17, 8:34 PM CDT	Severe Thunderstorm Warning	DMX	56 min

Nearby

Alerts in force now Tornadoes on record Forecast The radar archive

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.