Flash Flood Warnings in South Dakota
1,089 flash flood warnings since 1986. 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 since 1986. Tap one for its archive.
- Flash Flood Warnings
- 1,089
- Busiest year
- 201075 flash flood warnings
- Average year
- 27over 40 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.
By month of the year
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
From 2008 to 2025, 85% of flash flood reports in South Dakota fell inside a flash flood warning issued on average 81 minutes before, and 43% of the flash flood warnings had no report inside them.
Flash flood warnings by year
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| 2008 | 40 | 19 | 53% | 43 | 84% | 81 min |
| 2009 | 44 | 22 | 50% | 39 | 77% | 56 min |
| 2010 | 75 | 57 | 24% | 98 | 92% | 81 min |
| 2011 | 67 | 33 | 51% | 56 | 84% | 95 min |
| 2012 | 16 | 8 | 50% | 13 | 100% | 94 min |
| 2013 | 40 | 18 | 55% | 32 | 91% | 69 min |
| 2014 | 57 | 37 | 35% | 48 | 96% | 101 min |
| 2015 | 36 | 22 | 39% | 32 | 94% | 53 min |
| 2016 | 33 | 17 | 48% | 30 | 90% | 66 min |
| 2017 | 10 | 3 | 70% | 9 | 44% | 95 min |
| 2018 | 46 | 35 | 24% | 55 | 71% | 91 min |
| 2019 | 48 | 28 | 42% | 46 | 83% | 84 min |
| 2020 | 24 | 15 | 38% | 24 | 83% | 88 min |
| 2021 | 10 | 2 | 80% | 8 | 88% | 49 min |
| 2022 | 19 | 9 | 53% | 13 | 69% | 109 min |
| 2023 | 14 | 6 | 57% | 14 | 93% | 84 min |
| 2024 | 40 | 27 | 32% | 39 | 85% | 83 min |
| 2025 | 26 | 11 | 58% | 18 | 72% | 77 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.
By county
Every county with at least one alert. A county page lists each alert that covered it.
- Minnehaha County99
- Lincoln County90
- Union County89
- Pennington County66
- Clay County51
- Turner County49
- Charles Mix County46
- Yankton County43
- Lawrence County42
- Meade County42
- Custer County40
- Hamlin County39
- Moody County39
- Stanley County39
- Dewey County38
- Hutchinson County38
- Codington County37
- Davison County37
- Brown County36
- Gregory County35
- Deuel County34
- Aurora County34
- Hand County34
- Hughes County33
- Corson County33
- Lyman County32
- Bon Homme County32
- McCook County32
- Hyde County31
- Roberts County30
- Fall River County30
- Brule County30
- Douglas County30
- Spink County28
- Edmunds County28
- Brookings County27
- Hanson County27
- Day County26
- Lake County26
- Jackson County25
26 more counties
- Sully County25
- Faulk County25
- Potter County23
- Marshall County22
- Clark County21
- Sanborn County21
- Kingsbury County20
- Grant County20
- Beadle County20
- Haakon County19
- Ziebach County19
- Perkins County19
- Miner County19
- Tripp County18
- Todd County18
- McPherson County18
- Campbell County17
- Walworth County17
- Buffalo County16
- Mellette County16
- Jones County16
- Jerauld County14
- Butte County13
- Oglala Lakota County13
- Bennett County9
- Harding County8
The latest flash flood warnings
The most recent on file, newest first.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 7, 8:07 PM CDT | Flash Flood Warning | FSD | Charles Mix | 3 hr |
| Sep 6, 2:07 PM CDT | Flash Flood Warning | FSD | Brookings, Minnehaha, Moody | 4 hr |
| Sep 5, 4:38 AM CDT | Flash Flood Warning | FSD | Davison, Hanson, Hutchinson | 3 hr |
| Aug 20, 8:14 PM CDT | Flash Flood Warning | FSD | Lincoln, Turner | 96 min |
| Jul 30, 11:34 PM CDT | Flash Flood Warning | FSD | Kingsbury | 3 hr |
| Jul 30, 9:50 PM CDT | Flash Flood Warning | ABR | Hughes, Stanley | 3 hr |
| Jul 30, 6:25 PM CDT | Flash Flood Warning | ABR | Day, Marshall, Roberts | 6 hr |
| Jul 30, 4:51 PM CDT | Flash Flood Warning | ABR | Brown, Day | 6 hr |
| Jul 30, 4:17 PM CDT | Flash Flood Warning | ABR | Day | 6 hr |
| Jul 30, 4:09 PM CDT | Flash Flood Warning | ABR | Lyman | 6 hr |
| Jul 18, 3:01 PM CDT | Flash Flood Warning | UNR | Lawrence | 72 min |
| Jul 8, 1:43 AM CDT | Flash Flood Warning | ABR | Brown | 6 hr |
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.