Alert archive / Iowa / Cass County
Weather alerts in Cass County, Iowa, 2026
135 weather alerts in 2026, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered this county.
Cass County and its neighbors
Each county as a circle sized by its count in 2026. Tap one for its archive.
- Alerts
- 135
- Warnings
- 40
- Watches
- 31
- Advisories
- 19
- Busiest month
- June32 alerts
- Busiest day
- June 6, 202610 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
0 of 4 tornado warnings covering Cass County in 2026 had a tornado report inside them.
Cass County, 2026
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 4 | 0 | 100% | 0 | ||
| Severe thunderstorm warnings | 20 | 8 | 60% | 10 | 80% | 22 min |
| Flash flood warnings | 4 | 0 | 100% | 0 |
Each office's whole area, 2026
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Des Moines, IA: tornado warnings | 78 | 21 | 73% | 32 | 81% | 21 min |
| NWS Des Moines, IA: severe thunderstorm warnings | 343 | 160 | 53% | 469 | 84% | 23 min |
| NWS Des Moines, IA: flash flood warnings | 31 | 11 | 65% | 25 | 76% | 92 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 5, 8:25 PM CST | Dense Fog Advisory | DMX | 19 hr |
| Jan 20, 2:30 PM CST | Extreme Cold Watch | DMX | 45 hr |
| Jan 21, 2:29 AM CST | Wind Advisory | DMX | 12 hr |
| Jan 21, 11:27 AM CST | High Wind Warning | DMX | 8 hr |
| Jan 22, 2:28 AM CST | Extreme Cold Warning | DMX | 34 hr |
| Jan 22, 11:08 AM CST | Cold Weather Advisory | DMX | 40 hr |
| Jan 25, 2:04 AM CST | Cold Weather Advisory | DMX | 31 hr |
| Feb 15, 1:40 AM CST | Dense Fog Advisory | DMX | 7 hr |
| Feb 17, 2:41 PM CST | Fire Weather Watch | DMX | 6 hr |
| Feb 17, 5:22 PM CST | Mesoscale Discussion | SPC | 53 min |
| Feb 17, 8:15 PM CST | Red Flag Warning | DMX | 23 hr |
| Feb 18, 2:43 PM CST | Winter Weather Advisory | DMX | 42 hr |
| Feb 19, 10:45 AM CST | Winter Storm Warning | DMX | 22 hr |
| Feb 19, 6:07 PM CST | Mesoscale Discussion | SPC | 6 hr |
| Mar 6, 1:50 PM CST | Mesoscale Discussion | SPC | 2 hr |
| Mar 6, 3:16 PM CST | Tornado Watch | SPC | 9 hr |
| Mar 6, 5:23 PM CST | Mesoscale Discussion | SPC | 2 hr |
| Mar 6, 6:10 PM CST | Severe Thunderstorm Warning | DMX | 34 min |
| Mar 6, 7:12 PM CST | Mesoscale Discussion | SPC | 2 hr |
| Mar 11, 12:08 PM CDT | Red Flag Warning | DMX | 33 hr |
| Mar 12, 3:48 AM CDT | High Wind Watch | DMX | 6 hr |
| Mar 12, 10:04 AM CDT | Wind Advisory | DMX | 26 hr |
| Mar 12, 2:20 PM CDT | Winter Storm Watch | DMX | 45 hr |
| Mar 14, 3:09 AM CDT | High Wind Watch | DMX | 8 hr |
| Mar 14, 11:34 AM CDT | Blizzard Warning | DMX | 43 hr |
| Mar 14, 11:37 AM CDT | High Wind Warning | DMX | 40 hr |
| Mar 15, 9:49 AM CDT | Mesoscale Discussion | SPC | 6 hr |
| Mar 15, 8:21 PM CDT | Cold Weather Advisory | DMX | 14 hr |
| Mar 16, 5:37 AM CDT | Winter Weather Advisory | DMX | 4 hr |
| Mar 20, 9:07 PM CDT | Red Flag Warning | DMX | 25 hr |
| Mar 26, 1:42 PM CDT | Fire Weather Watch | DMX | 22 hr |
| Mar 26, 1:42 PM CDT | Red Flag Warning | DMX | 31 hr |
| Mar 27, 11:52 AM CDT | Red Flag Warning | DMX | 33 hr |
| Mar 30, 8:44 PM CDT | Severe Thunderstorm Warning | DMX | 46 min |
| Mar 30, 8:57 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Mar 30, 9:21 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Apr 6, 1:20 PM CDT | Winter Weather Advisory | DMX | 21 hr |
| Apr 7, 12:36 AM CDT | Mesoscale Discussion | SPC | 6 hr |
| Apr 15, 10:22 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| Apr 23, 11:13 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| Apr 23, 12:02 PM CDT | Tornado Watch | SPC | 7 hr |
| Apr 23, 2:37 PM CDT | Mesoscale Discussion | SPC | 83 min |
| Apr 23, 5:04 PM CDT | Mesoscale Discussion | SPC | 116 min |
| Apr 23, 5:15 PM CDT | Severe Thunderstorm Warning | DMX | 30 min |
| Apr 23, 5:39 PM CDT | Severe Thunderstorm Warning | DMX | 66 min |
| Apr 23, 6:25 PM CDT | Severe Thunderstorm Warning | DMX | 50 min |
| May 1, 2:34 AM CDT | Frost Advisory | DMX | 29 hr |
| May 15, 3:55 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| May 15, 5:16 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| May 15, 6:52 PM CDT | Severe Thunderstorm Warning | DMX | 53 min |
| May 15, 7:29 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| May 15, 10:53 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| May 16, 4:40 PM CDT | Tornado Watch | SPC | 6 hr |
| May 16, 5:34 PM CDT | Severe Thunderstorm Warning | DMX | 41 min |
| May 17, 7:40 PM CDT | Mesoscale Discussion | SPC | 65 min |
| May 17, 8:07 PM CDT | Tornado Watch | SPC | 5 hr |
| May 17, 9:30 PM CDT | Mesoscale Discussion | SPC | 90 min |
| May 17, 9:31 PM CDT | Severe Thunderstorm Warning | DMX | 59 min |
| May 18, 3:29 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| May 18, 3:49 PM CDT | Tornado Watch | SPC | 6 hr |
| May 31, 9:30 PM CDT | Severe Thunderstorm Watch | SPC | 7 hr |
| Jun 4, 3:54 AM CDT | Flood Watch | DMX | 27 hr |
| Jun 4, 1:29 PM CDT | Mesoscale Discussion | SPC | 3 hr |
| Jun 5, 12:43 PM CDT | Flood Watch | DMX | 17 hr |
| Jun 5, 3:55 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 5, 9:50 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jun 5, 9:59 PM CDT | Tornado Warning | DMX | 46 min |
| Jun 5, 10:10 PM CDT | Mesoscale Discussion | SPC | 95 min |
| Jun 5, 10:41 PM CDT | Severe Thunderstorm Warning | DMX | 64 min |
| Jun 5, 10:53 PM CDT | Severe Thunderstorm Warning | DMX | 67 min |
| Jun 5, 11:11 PM CDT | Tornado Warning | DMX | 20 min |
| Jun 5, 11:23 PM CDT | Flash Flood Warning | DMX | 4 hr |
| Jun 5, 11:28 PM CDT | Severe Thunderstorm Warning | DMX | 47 min |
| Jun 5, 11:33 PM CDT | Mesoscale Discussion | SPC | 87 min |
| Jun 5, 11:38 PM CDT | Severe Thunderstorm Warning | DMX | 67 min |
| Jun 8, 2:11 PM CDT | Heat Advisory | DMX | 30 hr |
| Jun 10, 11:02 AM CDT | Flood Watch | DMX | 29 hr |
| Jun 10, 1:35 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 11, 1:51 AM CDT | Mesoscale Discussion | SPC | 114 min |
| Jun 11, 2:13 AM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jun 11, 4:59 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 11, 5:59 AM CDT | Severe Thunderstorm Warning | DMX | 61 min |
| Jun 11, 6:10 AM CDT | Tornado Warning | DMX | 35 min |
| Jun 11, 6:15 AM CDT | Tornado Warning | DMX | 30 min |
| Jun 11, 6:33 AM CDT | Mesoscale Discussion | SPC | 87 min |
| Jun 11, 6:34 AM CDT | Severe Thunderstorm Warning | DMX | 41 min |
| Jun 13, 9:07 AM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Jun 13, 9:13 AM CDT | Severe Thunderstorm Warning | DMX | 47 min |
| Jun 13, 3:17 PM CDT | Mesoscale Discussion | SPC | 118 min |
| Jun 17, 2:36 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jun 27, 1:18 AM CDT | Extreme Heat Watch | DMX | 24 hr |
| Jun 27, 12:50 PM CDT | Extreme Heat Warning | DMX | 6 days |
| Jul 2, 1:05 PM CDT | Flood Watch | DMX | 42 hr |
| Jul 3, 9:16 PM CDT | Mesoscale Discussion | SPC | 119 min |
| Jul 8, 5:21 PM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Jul 8, 6:21 PM CDT | Mesoscale Discussion | SPC | 114 min |
| Jul 8, 9:53 PM CDT | Severe Thunderstorm Warning | DMX | 37 min |
| Jul 8, 10:08 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Jul 19, 12:53 PM CDT | Heat Advisory | DMX | 31 hr |
| Jul 24, 2:27 AM CDT | Heat Advisory | DMX | 58 hr |
| Jul 24, 2:27 AM CDT | Extreme Heat Watch | DMX | 57 hr |
| Jul 25, 2:53 AM CDT | Extreme Heat Warning | DMX | 67 hr |
| Jul 25, 4:48 AM CDT | Dense Fog Advisory | DMX | 5 hr |
| Jul 27, 12:49 PM CDT | Mesoscale Discussion | SPC | 116 min |
| Aug 5, 12:01 AM CDT | Mesoscale Discussion | SPC | 119 min |
| Aug 5, 12:07 AM CDT | Severe Thunderstorm Warning | DMX | 38 min |
| Aug 6, 12:43 AM CDT | Dense Fog Advisory | DMX | 9 hr |
| Aug 7, 2:52 AM CDT | Dense Fog Advisory | DMX | 6 hr |
| Aug 7, 1:16 PM CDT | Mesoscale Discussion | SPC | 119 min |
| Aug 8, 11:18 PM CDT | Mesoscale Discussion | SPC | 117 min |
| Aug 12, 2:24 AM CDT | Severe Thunderstorm Watch | SPC | 8 hr |
| Aug 12, 4:37 AM CDT | Mesoscale Discussion | SPC | 53 min |
| Aug 13, 1:31 AM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
| Aug 13, 2:53 AM CDT | Flood Watch | DMX | 55 hr |
| Aug 13, 4:49 AM CDT | Mesoscale Discussion | SPC | 116 min |
| Aug 14, 2:20 AM CDT | Mesoscale Discussion | SPC | 2 hr |
| Aug 14, 4:52 AM CDT | Flash Flood Warning | DMX | 3 hr |
| Aug 30, 1:32 PM CDT | Heat Advisory | DMX | 6 days |
| Sep 6, 2:45 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Sep 6, 4:42 PM CDT | Severe Thunderstorm Watch | SPC | 5 hr |
| Sep 8, 2:49 PM CDT | Mesoscale Discussion | SPC | 116 min |
| Sep 9, 1:49 AM CDT | Flash Flood Warning | DMX | 5 hr |
| Sep 13, 8:19 PM CDT | Flood Watch | DMX | 3 days |
| Sep 14, 10:33 AM CDT | Special Weather Statement | DMX | 42 min |
| Sep 14, 3:23 PM CDT | Mesoscale Discussion | SPC | 2 hr |
| Sep 14, 4:51 PM CDT | Tornado Watch | SPC | 7 hr |
| Sep 14, 6:18 PM CDT | Mesoscale Discussion | SPC | 57 min |
| Sep 14, 7:20 PM CDT | Mesoscale Discussion | SPC | 55 min |
| Sep 14, 7:40 PM CDT | Severe Thunderstorm Warning | DMX | 50 min |
| Sep 14, 8:24 PM CDT | Severe Thunderstorm Warning | DMX | 51 min |
| Sep 15, 1:28 AM CDT | Special Weather Statement | DMX | 32 min |
| Sep 15, 1:43 AM CDT | Severe Thunderstorm Warning | DMX | 32 min |
| Sep 15, 3:01 AM CDT | Flash Flood Warning | DMX | 4 hr |
| Sep 15, 8:08 AM CDT | River Flood Watch | DMX | 8 hr |
| Sep 16, 8:20 PM CDT | Dense Fog Advisory | DMX | 14 hr |
By product
Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordForecastThe radar archive2025
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.