Sioux County, Iowa
Recorded hazard history: storm events since 1950, federal disaster declarations since 1953, flood insurance claims since 1978, and FEMA's risk index.
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. NCEI storm records through 30 Jun 2026; OpenFEMA declarations refreshed 1 Oct 2026; NFIP claims as of 8 Sep 2026.
Sioux County, Iowa, has 1,046 weather events in the NCEI Storm Events record since 1950, most of them damaging wind.
That is 136.2 events per 100 square miles, in line with the Iowa figure of 124.6, and 291.4 per 10,000 residents against 218.0 statewide.
54 events fall in the 12 months to 30 Jun 2026. NCEI attributes 5 deaths and 12 injuries to events in the county, with property damage estimated at $37M and crop damage at $32M.
FEMA has designated the county in 15 federal disaster declarations since 1953; the most recent is Severe Storms, Flooding, Straight-Line Winds, And Tornadoes (major disaster, 24 Jun 2024).
National Flood Insurance Program policyholders in the county filed 43 claims since 1978, of which 37 were paid, totalling $4.0M (about $107K per paid claim). FEMA counts 151 residential flood policies in force.
FEMA's National Risk Index rates the county's overall risk as "Relatively Low" and its expected annual loss as "Relatively Low" ($30M a year across 18 hazards).
Compared with Iowa and the United States
| Measure | Sioux County | Iowa | US |
|---|---|---|---|
| Recorded events since 1950 | 1,046 | 69,606 | 1,977,440 |
| Events per 100 square miles | 136.2 | 124.6 | 56.0 |
| Events per 10,000 residents | 291.4 | 218.0 | 59.6 |
| Events in the last 12 months | 54 | 1,467 | 62,008 |
| Deaths recorded by NCEI | 5 | 223 | 26,435 |
| Property damage (NCEI estimates) | $37M | $6.5B | $575B |
| NFIP claims per 1,000 residents | 1.2 | 4.6 | 8.1 |
| Average paid NFIP claim | $107K | $30K | $43K |
| Claims per 100 policies in force, last 10 years | 20.5 | 21.8 | 16.1 |
County-recorded events plus zone-recorded events whose forecast zone is named for the county. State and US rows include events recorded only by forecast zone. Rates use 2021 Census population and land area.
Events by decade
Trend: 709 events in the 20 years to 2025 against 261 in the 20 years before. Reporting practice changed in 1996 and again with automated reports in the 2000s, so decade totals measure the record as much as the weather.
Events by type
Hazard pages exist for hail, tornado, flood, wind and winter where the county has at least 10 recorded events. "Other" covers heavy rain, debris flow, dust, funnel clouds and similar reports.
Largest recorded events
| Date | Event type | Group | Magnitude | Property damage | Crop damage | Deaths | Injuries | Geography |
|---|---|---|---|---|---|---|---|---|
| 14 Jan 2007 | Winter Storm | Winter | — | — | — | 2 | 3 | Forecast zone |
| 14 Jan 2021 | Blizzard | Winter | — | — | — | 1 | 1 | Forecast zone |
| 20 Jun 2024 | Flood | Flood | — | $6.5M | — | 1 | — | County |
| 24 Jul 2005 | Thunderstorm Wind | Wind | 79 mph | $50K | — | 1 | — | County |
| 21 Jul 2010 | Thunderstorm Wind | Wind | 100 mph | $200K | — | — | 4 | County |
| 18 Dec 2025 | Blizzard | Winter | — | — | — | — | 3 | Forecast zone |
| 26 Oct 2010 | High Wind | Wind | 58 mph | $50K | — | — | 1 | Forecast zone |
| 9 Apr 2013 | Winter Storm | Winter | — | $10M | — | — | — | Forecast zone |
| 1 Jul 2022 | Drought | Drought | — | — | $9.2M | — | — | Forecast zone |
| 1 Oct 2023 | Drought | Drought | — | — | $4.8M | — | — | Forecast zone |
| 1 Aug 2022 | Drought | Drought | — | — | $4.1M | — | — | Forecast zone |
| 11 May 2014 | Tornado | Tornado | EF1 | $3.0M | — | — | — | County |
| 1 Sep 2022 | Drought | Drought | — | — | $2.6M | — | — | Forecast zone |
| 22 Sep 1968 | Tornado | Tornado | F3 | $2.5M | — | — | — | County |
| 5 Jul 1978 | Tornado | Tornado | F2 | $2.5M | — | — | — | County |
| 8 Aug 1979 | Tornado | Tornado | F2 | $2.5M | — | — | — | County |
| 1 Jun 2019 | Flood | Flood | — | — | $2.3M | — | — | County |
| 1 Oct 2002 | Hail | Hail | 1.50 in | — | $2.0M | — | — | County |
| 5 Aug 2023 | Flash Flood | Flood | — | $1.5M | — | — | — | County |
| 1 Aug 2020 | Drought | Drought | — | — | $1.5M | — | — | Forecast zone |
Ranked by deaths, then injuries, then NCEI's damage estimate. Deaths and injuries are NCEI counts (direct plus indirect); no personal details are recorded here.
Federal disaster declarations
| Declared | Number | Type | Incident | Title | Programs |
|---|---|---|---|---|---|
| 24 Jun 2024 | DR-4796 | Major disaster | Severe Storm | Severe Storms, Flooding, Straight-Line Winds, And Tornadoes | Individual assistance, Public assistance |
| 23 Mar 2020 | DR-4483 | Major disaster | Biological | Covid-19 Pandemic | Individual assistance, Public assistance |
| 13 Mar 2020 | EM-3480 | Emergency | Biological | Covid-19 | Public assistance |
| 23 Mar 2019 | DR-4421 | Major disaster | Flood | Severe Storms And Flooding | Public assistance |
| 20 Aug 2018 | DR-4386 | Major disaster | Severe Storm | Severe Storms, Tornadoes, Straight-Line Winds, And Flooding | Public assistance |
| 24 Jul 2014 | DR-4184 | Major disaster | Flood | Severe Storms, Tornadoes, Straight-Line Winds, And Flooding | Public assistance |
| 2 Jul 2013 | DR-4126 | Major disaster | Severe Storm | Severe Storms, Tornadoes, And Flooding | Public assistance |
| 6 May 2013 | DR-4114 | Major disaster | Severe Storm | Severe Winter Storm | Public assistance |
| 29 Jul 2010 | DR-1930 | Major disaster | Severe Storm | Severe Storms, Flooding, And Tornadoes | Individual assistance, Public assistance |
| 25 Feb 2010 | DR-1877 | Major disaster | Severe Storm | Severe Winter Storms And Snowstorm | Public assistance |
| 10 Sep 2005 | EM-3239 | Emergency | Hurricane | Hurricane Katrina Evacuation | Public assistance |
| 9 Jul 1993 | DR-996 | Major disaster | Flood | Severe Storms & Flooding | Individual assistance, Public assistance |
| 31 Mar 1977 | EM-3036 | Emergency | Drought | Drought | Public assistance |
| 25 Apr 1969 | DR-259 | Major disaster | Flood | Flooding | Individual assistance, Public assistance |
| 22 Apr 1965 | DR-193 | Major disaster | Flood | Flooding | Individual assistance, Public assistance |
Declarations in which FEMA designated this county, from the OpenFEMA Disaster Declarations Summaries (v2). DR: major disaster; EM: emergency; FM: fire management assistance. Programs show whether individual or public assistance was made available.
Flood insurance claims
| Year of loss | Claims | Paid claims | Amount paid | Average paid |
|---|---|---|---|---|
| 2024 | 25 | 25 | $3,787,664 | $151,507 |
| 2019 | 1 | 1 | $1,888 | $1,888 |
| 2018 | 5 | 5 | $110,349 | $22,070 |
| 2016 | 1 | 0 | $0 | — |
| 2014 | 6 | 3 | $22,847 | $7,616 |
| 2013 | 1 | 1 | $38,421 | $38,421 |
| 2011 | 2 | 1 | $3,407 | $3,407 |
| 2010 | 2 | 1 | $1,569 | $1,569 |
OpenFEMA NFIP claims (v3, as of 8 Sep 2026), aggregated by year of loss; amounts are building, contents and increased-cost-of-compliance payments as recorded. Repetitive-loss counts from the NFIP Multiple Loss Properties file (2 Aug 2026); policies in force from the NFIP Residential Penetration Rates file (3 Aug 2026).
National Risk Index
| Hazard (NRI) | Risk rating | Expected annual loss |
|---|---|---|
| Inland flooding | $11,364,061 | |
| Tornado | $6,614,758 | |
| Hail | $5,655,634 | |
| Cold wave | $2,517,376 | |
| Drought | $1,000,019 | |
| Strong wind | $934,477 | |
| Winter weather | $557,274 | |
| Ice storm | $420,588 | |
| Heat wave | $412,276 | |
| Lightning | $186,882 | |
| Earthquake | $45,517 | |
| Wildfire | $44,287 | |
| Landslide | $538 |
FEMA National Risk Index, December 2025 release. Ratings are FEMA's relative comparison of counties; expected annual loss is FEMA's modelled estimate of average yearly building, population and agriculture loss. See how to read the NRI.
Hurricane and tropical storm passes
No HURDAT2 track at tropical-storm strength passes within 100 miles of the county's centre point (through the 2025 season).
ZIP codes with flood claims
ZIP codes whose NFIP claims carry this county's code, with the number of claims. Five or more claims are needed for a ZIP page to be indexed.
Questions and answers
How often does it hail in Sioux County, IA?
NCEI records 261 hail events in Sioux County since 1950, in 44 different years; that is about 3.4 recorded events a year. 53 reports were golf-ball size (1.75 in) or larger.
Has Sioux County had a tornado?
Yes. NCEI records 47 tornadoes in Sioux County since 1950, 7 of them rated (E)F2 or stronger. Tornado deaths recorded: 0.
When was the last federal disaster declaration for Sioux County?
24 Jun 2024: Severe Storms, Flooding, Straight-Line Winds, And Tornadoes, a major disaster declaration for severe storm. The county appears in 15 declarations since 1953.
How many flood insurance claims have been filed in Sioux County, and how much was paid?
43 NFIP claims since 1978, 37 of them paid, for $4.0M in total. FEMA publishes these figures redacted and aggregated; individual properties are not identified.
Is Sioux County in the National Risk Index's high-risk band?
FEMA's National Risk Index (December 2025) rates the county "Relatively Low" for overall risk, "Relatively Low" for expected annual loss, "Very Low" for social vulnerability and "Very High" for community resilience. These ratings are FEMA's relative comparison across all US counties.
How does Sioux County compare with the rest of Iowa?
136.2 recorded events per 100 square miles against 124.6 statewide, and 1.2 NFIP claims per 1,000 residents against 4.6. The comparison table on this page shows each measure beside the state and national figures.
Provenance
Storm events: NOAA NCEI Storm Events Database, yearly details files through 30 Jun 2026 (public domain). Declarations: OpenFEMA DisasterDeclarationsSummaries v2, refreshed 1 Oct 2026. Flood claims: OpenFEMA NfipClaims v3 as of 8 Sep 2026; NfipMultipleLossProperties v1 (2 Aug 2026); NfipResidentialPenetrationRates v1 (3 Aug 2026). Risk index: FEMA National Risk Index, December 2025. Hurricane tracks: NHC HURDAT2 through 2025. Population and area: US Census Bureau, 2021 vintage. Built 1 Oct 2026; see the methodology and corrections pages. Hazard hubs: Hail · Tornado · Flood · Wind · Winter.