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Flood in Walworth County, South Dakota
18 floods and flash floods events in the NCEI Storm Events record, 1950 to 2026. Event types counted: Flood, Flash Flood, Coastal Flood, Lakeshore Flood.
NCEI notes that Storm Data is compiled from a variety of sources including the National Weather Service, other federal, state and local agencies, the media and the public; that property and crop damage figures are estimates; and that some events are recorded by NWS forecast zone rather than by county. FEMA notes that NFIP claim records are redacted and aggregated to protect the privacy of policyholders. Storm records through 30 Jun 2026.
NCEI records 18 flood events in Walworth County, South Dakota, between 1950 and 2026, spread over 8 years.
June is the busiest month, with 5 of the recorded events. The last 20 years account for 14 events against 4 in the 20 years before, a change that reflects reporting practice as much as weather.
The county holds 0.5% of the 3,390 flood events recorded in South Dakota; its 2.5 per 100 square miles compares with 4.5 statewide.
Compared with South Dakota
| Measure | Walworth County | South Dakota | US |
|---|---|---|---|
| Flood events since 1950 | 18 | 3,390 | 183,559 |
| Per 100 square miles | 2.5 | 4.5 | 5.2 |
| Per 10,000 residents | 34.3 | 37.9 | 5.5 |
| Deaths recorded | 0 | 10 | 2,961 |
| Busiest month | June | June | June |
By year
Seasonality
0Feb
0Mar
2Apr
2May
4Jun
5Jul
2Aug
3Sep
0Oct
0Nov
0Dec
0
Recorded events
All 18 events, most recent first. Magnitude is hail size, tornado rating or wind speed as recorded.
| Date | Event type | Magnitude | Property damage | Crop damage | Deaths | Injuries | Geography |
|---|---|---|---|---|---|---|---|
| 1 Jun 2019 | Flood | — | — | $3.2M | — | — | County |
| 1 May 2019 | Flood | — | — | — | — | — | County |
| 1 Apr 2019 | Flood | — | $292K | — | — | — | County |
| 25 Mar 2019 | Flood | — | — | — | — | — | County |
| 18 May 2018 | Flash Flood | — | — | — | — | — | County |
| 17 May 2018 | Flash Flood | — | $3.0M | — | — | — | County |
| 17 May 2018 | Flood | — | — | — | — | — | County |
| 18 Jun 2014 | Flash Flood | — | — | — | — | — | County |
| 20 Jun 2011 | Flood | — | — | — | — | — | County |
| 14 Jun 2011 | Flash Flood | — | — | — | — | — | County |
| 14 Jul 2009 | Flash Flood | — | — | — | — | — | County |
| 18 Aug 2007 | Flood | — | — | — | — | — | County |
| 17 Aug 2007 | Flash Flood | — | — | — | — | — | County |
| 17 Jun 2007 | Flash Flood | — | — | — | — | — | County |
| 26 Aug 1998 | Flood | — | — | — | — | — | Forecast zone |
| 11 Jul 1997 | Flash Flood | — | — | — | — | — | County |
| 1 Apr 1997 | Flood | — | — | — | — | — | Forecast zone |
| 21 Mar 1997 | Flood | — | — | — | — | — | Forecast zone |
Questions and answers
How many flood events has Walworth County had?
18 events in the NCEI Storm Events record between 1950 and 2026. Reporting of floods and flash floods became far more complete after 1996, so early decades undercount.
When was the last recorded flood event in Walworth County?
1 Jun 2019 (Flood). Records reach NCEI about 120 days after the month ends.
What was the most damaging flood event recorded in Walworth County?
The flood of 1 Jun 2019, with property damage estimated by NCEI at $0 and crop damage at $3.2M.
How does Walworth County compare with South Dakota for flood?
2.5 events per 100 square miles against 4.5 statewide; the county holds 18 of the state's 3,390 recorded events.
Provenance
NOAA NCEI Storm Events Database, yearly details files through 30 Jun 2026, public domain. County-recorded events plus zone-recorded events whose forecast zone is named for the county (marked "Forecast zone"). Population and area from the US Census Bureau (2021). Built 1 Oct 2026. See the methodology, the Flood hub and the county page.