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Flood in Sioux County, North Dakota
14 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.
Sioux County, North Dakota, has 14 flood events in the NCEI record since 1950, with at least one in 8 different years.
June is the busiest month, with 5 of the recorded events. The last 20 years account for 7 events against 7 in the 20 years before, a change that reflects reporting practice as much as weather.
The county holds 1.1% of the 1,221 flood events recorded in North Dakota; its 1.3 per 100 square miles compares with 1.8 statewide.
NCEI attributes 2 deaths in the county to floods and flash floods.
Compared with North Dakota
| Measure | Sioux County | North Dakota | US |
|---|---|---|---|
| Flood events since 1950 | 14 | 1,221 | 183,559 |
| Per 100 square miles | 1.3 | 1.8 | 5.2 |
| Per 10,000 residents | 37.5 | 15.8 | 5.5 |
| Deaths recorded | 2 | 16 | 2,961 |
| Busiest month | June | June | June |
By year
Seasonality
0Feb
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2Apr
1May
1Jun
5Jul
4Aug
1Sep
0Oct
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Recorded events
All 14 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 |
|---|---|---|---|---|---|---|---|
| 8 Jul 2019 | Flash Flood | — | $750K | — | 2 | 2 | County |
| 25 May 2013 | Flash Flood | — | $250K | $50K | — | — | County |
| 1 Aug 2011 | Flood | — | — | — | — | — | County |
| 1 Jul 2011 | Flood | — | — | — | — | — | County |
| 2 Jun 2011 | Flood | — | $250K | — | — | — | County |
| 1 Apr 2009 | Flood | — | $166K | — | — | — | County |
| 6 Mar 2009 | Flood | — | $264K | — | — | — | County |
| 7 Jun 2005 | Flash Flood | — | $18K | — | — | — | County |
| 7 Jun 2005 | Flash Flood | — | $50K | — | — | — | County |
| 7 Jun 2005 | Flash Flood | — | $70K | — | — | — | County |
| 16 Jul 2001 | Flash Flood | — | — | — | — | — | County |
| 15 Jul 2001 | Flash Flood | — | — | — | — | — | County |
| 18 Jun 1998 | Flash Flood | — | $3K | — | — | — | County |
| 21 Mar 1997 | Flood | — | $50K | — | — | — | Forecast zone |
Questions and answers
How many flood events has Sioux County had?
14 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 Sioux County?
8 Jul 2019 (Flash Flood). Records reach NCEI about 120 days after the month ends.
What was the most damaging flood event recorded in Sioux County?
The flash flood of 8 Jul 2019, with property damage estimated by NCEI at $750K; 2 deaths recorded.
How does Sioux County compare with North Dakota for flood?
1.3 events per 100 square miles against 1.8 statewide; the county holds 14 of the state's 1,221 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.