Alert archive / Wisconsin / Flash Flood Warnings
Flash Flood Warnings in Wisconsin, 2026
38 flash flood warnings in 2026. An alert counts here when it covered any part of the state, so the counties below add up to more than the state. The archive of flash flood warnings reaches back to 1986.
Flash Flood Warnings by county
Each county as a circle sized by its count in 2026. Tap one for its archive.
- Flash Flood Warnings
- 38
- Busiest month
- April23 flash flood warnings
- Busiest day
- April 17, 20267 flash flood warnings
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
16 of 38 flash flood warnings covering Wisconsin in 2026 had a flash flood report inside them; 37 of 57 flash flood reports fell inside a warning, on average 46 minutes after it went out.
Wisconsin, 2026
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Flash flood warnings | 38 | 16 | 58% | 57 | 65% | 46 min |
Each office's whole area, 2026
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Milwaukee, WI: flash flood warnings | 22 | 8 | 64% | 24 | 58% | 40 min |
| NWS La Crosse, WI: flash flood warnings | 16 | 7 | 56% | 21 | 76% | 142 min |
| NWS Twin Cities, MN: flash flood warnings | 11 | 6 | 45% | 11 | 91% | 57 min |
| NWS Green Bay, WI: flash flood warnings | 12 | 8 | 33% | 31 | 74% | 50 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 | Counties | Lasted |
|---|---|---|---|---|
| Apr 3, 8:58 PM CDT | Flash Flood Warning | ARX | La Crosse, Monroe, Vernon | 4 hr |
| Apr 13, 5:22 PM CDT | Flash Flood Warning | GRB | Marathon, Portage, Wood | 5 hr |
| Apr 13, 8:06 PM CDT | Flash Flood Warning | GRB | Marathon, Outagamie, Portage, Shawano, Waupaca | 8 hr |
| Apr 13, 10:01 PM CDT | Flash Flood Warning | GRB | Brown, Door, Kewaunee, Oconto, Outagamie | 6 hr |
| Apr 13, 10:04 PM CDT | Flash Flood Warning | ARX | Monroe | 3 hr |
| Apr 13, 10:54 PM CDT | Flash Flood Warning | GRB | Brown, Calumet, Kewaunee, Manitowoc, Outagamie, Winnebago | 5 hr |
| Apr 14, 10:16 AM CDT | Flash Flood Warning | GRB | Waupaca | 6 hr |
| Apr 14, 6:11 PM CDT | Flash Flood Warning | MKX | Dane, Dodge, Jefferson | 4 hr |
| Apr 14, 7:10 PM CDT | Flash Flood Warning | MKX | Dodge, Milwaukee, Ozaukee, Washington, Waukesha | 3 hr |
| Apr 14, 7:58 PM CDT | Flash Flood Warning | MKX | Milwaukee, Waukesha | 3 hr |
| Apr 14, 9:11 PM CDT | Flash Flood Warning | GRB | Brown | 3 hr |
| Apr 15, 7:26 PM CDT | Flash Flood Warning | MKX | Dane, Green, Jefferson, Lafayette, Rock, Walworth | 3 hr |
| Apr 15, 8:03 PM CDT | Flash Flood Warning | MKX | Dodge, Jefferson, Milwaukee, Ozaukee, Washington, Waukesha | 3 hr |
| Apr 15, 8:52 PM CDT | Flash Flood Warning | MKX | Kenosha, Racine, Rock, Walworth | 3 hr |
| Apr 17, 4:00 PM CDT | Flash Flood Warning | MKX | Lafayette | 3 hr |
| Apr 17, 4:10 PM CDT | Flash Flood Warning | GRB | Marathon, Wood | 5 hr |
| Apr 17, 5:15 PM CDT | Flash Flood Warning | MKX | Green, Lafayette | 4 hr |
| Apr 17, 5:19 PM CDT | Flash Flood Warning | MKX | Iowa | 3 hr |
| Apr 17, 6:08 PM CDT | Flash Flood Warning | MKX | Green, Rock | 3 hr |
| Apr 17, 6:34 PM CDT | Flash Flood Warning | MKX | Rock | 3 hr |
| Apr 17, 6:52 PM CDT | Flash Flood Warning | GRB | Langlade, Marathon, Menominee, Shawano | 2 hr |
| Apr 17, 7:01 PM CDT | Flash Flood Warning | MKX | Jefferson, Rock, Walworth | 2 hr |
| Apr 17, 7:43 PM CDT | Flash Flood Warning | MKX | Jefferson, Milwaukee, Racine, Walworth, Waukesha | 2 hr |
| Jun 11, 4:34 PM CDT | Flash Flood Warning | MKX | Green, Rock | 3 hr |
| Jun 11, 5:23 PM CDT | Flash Flood Warning | MKX | Rock | 103 min |
| Jun 24, 4:14 PM CDT | Flash Flood Warning | MKX | Green, Rock, Walworth | 3 hr |
| Jun 24, 6:29 PM CDT | Flash Flood Warning | GRB | Brown | 3 hr |
| Jul 1, 10:51 PM CDT | Flash Flood Warning | GRB | Brown, Calumet, Outagamie, Winnebago | 3 hr |
| Jul 1, 11:26 PM CDT | Flash Flood Warning | GRB | Portage, Waupaca, Waushara, Wood | 3 hr |
| Jul 1, 11:30 PM CDT | Flash Flood Warning | ARX | Adams | 3 hr |
| Jul 8, 4:20 PM CDT | Flash Flood Warning | GRB | Brown | 3 hr |
| Jul 8, 10:24 PM CDT | Flash Flood Warning | MKX | Ozaukee, Washington | 3 hr |
| Jul 27, 11:52 AM CDT | Flash Flood Warning | MKX | Kenosha, Racine | 108 min |
| Aug 10, 12:25 AM CDT | Flash Flood Warning | MKX | Racine, Walworth | 70 min |
| Sep 3, 9:19 AM CDT | Flash Flood Warning | MKX | Milwaukee, Ozaukee, Washington, Waukesha | 2 hr |
| Sep 4, 5:56 AM CDT | Flash Flood Warning | MKX | Sheboygan | 3 hr |
| Sep 19, 12:21 AM CDT | Flash Flood Warning | ARX | Vernon | 4 hr |
| Sep 19, 1:17 AM CDT | Flash Flood Warning | MKX | Dane | 2 hr |
By county
Every county with at least one alert. A county page lists each alert that covered it.
- Rock County8
- Brown County6
- Walworth County6
- Jefferson County5
- Milwaukee County5
- Waukesha County5
- Green County5
- Marathon County4
- Outagamie County4
- Ozaukee County4
- Washington County4
- Racine County4
- Portage County3
- Wood County3
- Waupaca County3
- Dane County3
- Dodge County3
- Lafayette County3
- Monroe County2
- Vernon County2
- Shawano County2
- Kewaunee County2
- Calumet County2
- Winnebago County2
- Kenosha County2
- La Crosse County1
- Door County1
- Oconto County1
- Manitowoc County1
- Iowa County1
- Langlade County1
- Menominee County1
- Waushara County1
- Adams County1
- Sheboygan County1
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
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.