States › South Dakota › Lyman County › Flood
Flood in Lyman County, South Dakota
38 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.
Lyman County, South Dakota, has 38 flood events in the NCEI record since 1950, with at least one in 15 different years.
June is the busiest month, with 11 of the recorded events. The last 20 years account for 29 events against 9 in the 20 years before, a change that reflects reporting practice as much as weather.
The county holds 1.1% of the 3,390 flood events recorded in South Dakota; its 2.3 per 100 square miles compares with 4.5 statewide.
NCEI attributes 2 deaths in the county to floods and flash floods.
Compared with South Dakota
| Measure | Lyman County | South Dakota | US |
|---|---|---|---|
| Flood events since 1950 | 38 | 3,390 | 183,559 |
| Per 100 square miles | 2.3 | 4.5 | 5.2 |
| Per 10,000 residents | 101.0 | 37.9 | 5.5 |
| Deaths recorded | 2 | 10 | 2,961 |
| Busiest month | June | June | June |
By year
Seasonality
0Feb
3Mar
5Apr
3May
7Jun
11Jul
5Aug
3Sep
0Oct
1Nov
0Dec
0
Recorded events
All 38 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 |
|---|---|---|---|---|---|---|---|
| 3 Aug 2025 | Flash Flood | — | — | — | — | — | County |
| 20 Jun 2024 | Flash Flood | — | — | — | — | — | County |
| 8 Feb 2024 | Flood | — | — | — | — | — | County |
| 13 Oct 2023 | Flood | — | — | — | — | — | County |
| 2 Aug 2019 | Flash Flood | — | — | — | — | — | County |
| 1 Jun 2019 | Flood | — | — | $5.0M | — | — | County |
| 26 May 2019 | Flood | — | — | — | — | — | County |
| 22 May 2019 | Flood | — | — | — | — | — | County |
| 22 May 2019 | Flood | — | — | — | — | — | County |
| 1 May 2019 | Flood | — | — | — | — | — | County |
| 1 Apr 2019 | Flood | — | $26K | — | — | — | County |
| 26 Mar 2019 | Flood | — | — | — | — | — | County |
| 14 Mar 2019 | Flood | — | — | — | — | — | County |
| 27 Jun 2018 | Flash Flood | — | — | — | — | — | County |
| 21 Jun 2018 | Flood | — | — | — | — | — | County |
| 26 Jul 2016 | Flash Flood | — | — | — | — | — | County |
| 28 Apr 2014 | Flood | — | — | — | — | — | County |
| 1 Aug 2011 | Flood | — | — | — | — | — | County |
| 1 Jul 2011 | Flood | — | — | — | — | — | County |
| 22 Jun 2011 | Flood | — | — | — | — | — | County |
| 20 Jun 2011 | Flash Flood | — | — | — | 2 | — | County |
| 20 Jun 2011 | Flood | — | — | — | — | — | County |
| 12 Jun 2011 | Flood | — | — | — | — | — | County |
| 2 Mar 2011 | Flood | — | — | — | — | — | County |
| 16 Feb 2011 | Flood | — | — | — | — | — | County |
| 10 Jul 2010 | Flash Flood | — | — | — | — | — | County |
| 8 Mar 2010 | Flood | — | — | — | — | — | County |
| 11 Feb 2009 | Flood | — | $5K | — | — | — | County |
| 12 Jun 2007 | Flash Flood | — | — | — | — | — | County |
| 13 May 2005 | Flood | — | — | — | — | — | Forecast zone |
| 1 Jul 2003 | Flash Flood | — | — | — | — | — | County |
| 1 Jul 2003 | Flash Flood | — | — | — | — | — | County |
| 11 Jun 2003 | Flash Flood | — | — | — | — | — | County |
| 9 May 1999 | Flash Flood | — | — | — | — | — | County |
| 3 Jun 1997 | Flood | — | — | — | — | — | Forecast zone |
| 1 May 1997 | Flood | — | — | — | — | — | Forecast zone |
| 1 Apr 1997 | Flood | — | — | — | — | — | Forecast zone |
| 21 Mar 1997 | Flood | — | — | — | — | — | Forecast zone |
Questions and answers
How many flood events has Lyman County had?
38 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 Lyman County?
3 Aug 2025 (Flash Flood). Records reach NCEI about 120 days after the month ends.
What was the most damaging flood event recorded in Lyman County?
The flood of 1 Jun 2019, with property damage estimated by NCEI at $0 and crop damage at $5.0M.
How does Lyman County compare with South Dakota for flood?
2.3 events per 100 square miles against 4.5 statewide; the county holds 38 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.