2 flood insurance claims·$374 paid·9 federal flood & hurricane disasters
Share of the whole county outline, rivers and lakes included; parts FEMA hasn’t mapped count as zero.
Shaded areas are FEMA’s mapped flood hazard zones in and around Sioux County, North Dakota. Zoomed out they are simplified; at street level the map switches to FEMA’s exact layer. Tap anywhere to check that spot, or search an address above.
In flood insurance claims here that reported a flood depth, the average was 1 inches.
Drawn to scale against an 80-inch door. Even a few inches soaks flooring, the bottom of the drywall and anything plugged in near the floor.
Average of the depths reported on claims (zero and implausible values left out); FEMA’s record doesn’t say exactly where each depth was measured. Source: OpenFEMA NFIP claims.
6 NOAA storm reports from Sioux County describe what happened, in the words of the forecasters who covered it. Read the North Dakota flood stories →
22 federal disaster declarations since 1969, 9 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Severe Storm, Tornadoes, And Straight-line Winds | Jun 20, 2025 |
| Severe Storm, Straight-line Winds, And Flooding | Jun 7, 2021 |
| Severe Winter Storm | Oct 4, 2013 |
| Flooding | Apr 5, 2011 |
| Flooding | Feb 14, 2011 |
| Severe Winter Storm | Apr 1, 2010 |
| Severe Winter Storm | Jan 20, 2010 |
| Severe Storms And Flooding | Mar 13, 2009 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
14 since 1996: 8 flash floods and 6 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flash Flood | Jul 8, 2019 | $750,000 · 2 killed |
| Flash Flood | May 25, 2013 | $250,000 |
| Flood | Jun 2, 2011 | $250,000 |
| Flood | Jul 1, 2011 | — |
| Flood | Aug 1, 2011 | — |
| Flood | Mar 6, 2009 | $264,000 |
| Flood | Apr 1, 2009 | $166,000 |
| Flash Flood | Jun 7, 2005 | $70,000 |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flash Flood · Jul 8, 2019. A surface boundary stretching from southwest into north central North Dakota served as the primary focal point for thunderstorm development in an atmosphere of very high instability. Initially, large hail was the main threat, though a couple of tornadoes developed in an area of enhanced low level shear. Later, storms mainly developed along an old outflow boundary and were slow moving. This combined with a moisture…
Flash Flood · May 25, 2013. Tornado Watch number 217 was in effect during this event.||Thunderstorms developing in the afternoon, in the warm sector of an area of low pressure, continued into the evening as an upper level short wave trough moved into the Dakotas. While the tornado threat did materialize as predicted, steep mid-level lapse rates, Mean Layer CAPE over 2000 Joules/KG, and deep layer shear to 45 knots supported updraft longevity…
Flood · Jun 2, 2011. This was part of historic flooding in North Dakota with statewide costs estimated around 1.5 billion dollars. Flooding was the result of significant winter snows and significant spring rains, not only in North Dakota but in Montana as well. Rocky Mountain snowpack was four to six times normal. Flooding was along the Missouri River from the Garrison Dam to the South Dakota border. Dams were overwhelmed by the amoun…
Flood · Jul 1, 2011. This was part of historic flooding in North Dakota with statewide costs estimated around 1.5 billion dollars. Flooding was the result of significant winter snows and significant spring rains, not only in North Dakota but in Montana as well. Rocky Mountain snowpack was four to six times normal. Flooding was along the Missouri River from the Garrison Dam to the South Dakota border. Dams were overwhelmed by the amoun…
National Weather Service narratives, lightly trimmed. Source: NOAA Storm Events Database.
Every colour on the map above is a place on this drawing: where the ground sits relative to the flood FEMA plans for.
If a building in Sioux County is in a high-risk zone (A or V) and its mortgage comes from a federally regulated or insured lender, or is federally backed, flood insurance is required.
Outside those zones it is optional, and often worth having: from 2014 to 2024 nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area. Since Risk Rating 2.0, NFIP premiums are set for each building, so the only reliable price is a quote: FloodSmart.gov or a local agent.