43 flood insurance claims·$4.0M paid·5 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, Iowa. 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.
River flooding and flash flooding from summer thunderstorms dominate the flood risk profile in Sioux County, Iowa, which recorded 122 flood events and 41 flash flood events over the last 30 years, resulting in one death.
Severe weather events, such as those driven by high moisture content and slow-moving storms in June 2025 and prolonged heavy rainfall in July 2025, have produced localized flash flooding and rainfall rates of 3 to 5 inches per hour across northwest Iowa. National Flood Insurance Program records show that flood losses extend across multiple zones. Properties located in FEMA Zone A experienced the highest impact with 31 claims averaging $134,250 and an average recorded water depth of 4 inches. Meanwhile, properties in Zone X recorded 9 claims averaging $66,656 with an average water depth of 4 inches, and Zone X_UNSHADED recorded 3 claims averaging $3,330 with an average water depth of 3 inches.
Homeowners, real estate agents, and journalists should pay the most attention to properties situated in high-risk Zone A areas where claims and payout averages are significantly higher, as well as properties located in moderate-to-low risk Zone X areas where historical claims indicate that damaging water depths still occur during heavy precipitation events.
Summary written from NOAA storm reports and NFIP claims for this county. Not a prediction.
9% of Sioux County’s flood insurance claims were on properties rated outside FEMA’s high-risk zones.
34 NFIP claims with a recorded rated flood zone, 1978 to date. The zone is the one FEMA used to rate that policy, which may not match today’s map. Source: OpenFEMA NFIP claims.
In flood insurance claims here that reported a flood depth, the average was 4 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.
The worst year was 2024, with 25 claims and $3.8M paid, the year of Severe Storms, Flooding, Straight-line Winds, and Tornadoes.
Bar height is scaled by square root so ordinary years stay visible next to the worst one. NFIP claims by year of loss. Source: OpenFEMA.
55 NOAA storm reports from Sioux County describe what happened, in the words of the forecasters who covered it. Read the Iowa flood stories →
15 federal disaster declarations since 1965, 5 of them floods, coastal storms or hurricanes.
| Disaster | Began |
|---|---|
| Severe Storms, Flooding, Straight-line Winds, And Tornadoes | Jun 16, 2024 |
| Severe Storms And Flooding | Mar 12, 2019 |
| Severe Storms, Tornadoes, Straight-line Winds, And Flooding | Jun 6, 2018 |
| Severe Storms, Tornadoes, Straight-line Winds, And Flooding | Jun 14, 2014 |
| Severe Storms, Tornadoes, And Flooding | May 19, 2013 |
| Severe Winter Storm | Apr 9, 2013 |
| Severe Storms, Flooding, And Tornadoes | Jun 1, 2010 |
| Severe Winter Storms And Snowstorm | Dec 23, 2009 |
Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.
163 since 1996: 41 flash floods and 122 river or area floods.
| Event | Date | Damage |
|---|---|---|
| Flood | Jul 30, 2025 | — |
| Flash Flood | Jul 30, 2025 | — |
| Flash Flood | Jul 29, 2025 | — |
| Flood | Jun 2, 2025 | — |
| Flash Flood | Jun 2, 2025 | — |
| Flood | Jun 22, 2024 | — |
| Flood | Jun 21, 2024 | — |
| Flash Flood | Jun 21, 2024 | — |
— = no damage estimate in the record. Source: NOAA Storm Events Database.
Flood · Jul 30, 2025. A wet period at the end of the July resulted in saturated soils and increased runoff, allowing for isolated river flooding through portions of the Floyd River Basin. The sharpest rises were observed with a heavy rain on the night of July 29 into the morning of July 30.
Flash Flood · Jul 30, 2025. Thunderstorms erupted within a very moist and unstable environment across central South Dakota during the afternoon of July 29 in response to an approaching upper level short-wave from Colorado. These thunderstorms quickly grew upscale into a line, producing 55 to 75 mph wind gusts across southeast South Dakota and extreme northeast Nebraska, resulting in isolated tree damage. In addition, prolonged heavy rain res…
Flash Flood · Jul 29, 2025. Thunderstorms erupted within a very moist and unstable environment across central South Dakota during the afternoon of July 29 in response to an approaching upper level short-wave from Colorado. These thunderstorms quickly grew upscale into a line, producing 55 to 75 mph wind gusts across southeast South Dakota and extreme northeast Nebraska, resulting in isolated tree damage. In addition, prolonged heavy rain res…
Flood · Jun 2, 2025. Locally heavy rainfall from thunderstorms resulted in quick, but brief rises on smaller creeks and streams in the immediate area. These elevated levels quickly fell back below flood stage as water moved downstream.
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.