O'Brien County, Iowa
Natural disaster risk, federal disaster history and flood insurance facts.
O'Brien County, Iowa has a very low overall risk from natural hazards in FEMA's National Risk Index. Its risk score is lower than 84% of US counties. It ranks 91st of 99 counties in Iowa. The costliest hazards here are inland flooding, tornadoes and hail. FEMA estimates about $11 million a year in expected losses, or roughly $786 per resident. Since 1965 it has been included in 13 federal disaster or emergency declarations for natural events (11 major disasters). The most recent was in June 2024 (severe storms, flooding, straight-line winds and tornadoes). Only 5 homes here carry federal flood insurance.
FEMA National Risk Index December 2025; OpenFEMA declarations to Nov 6, 2026; NFIP records. Updated November 6, 2026.
Top risks in O'Brien County
- Check the FEMA flood map for your address, and ask the seller or landlord about past flooding.
- Price a flood policy now. Most new federal policies take 30 days to start.
- Pick a shelter spot: a basement, or an inside room on the lowest floor with no windows.
- Turn on emergency alerts on your phone and keep a weather radio.
- Ask about the roof age and any impact-rated shingles.
- Check your home policy for a separate wind and hail deductible.
All 18 hazards
What the ratings mean ›| Hazard | Rating | Score | Expected loss a year | |
|---|---|---|---|---|
| Inland flooding | 18.5 | $4M | ||
| Tornado | 48.7 | $2M | ||
| Hail | 82.2 | $2M | ||
| Cold wave | 47.3 | $2M | ||
| Drought | 67.1 | $769K | ||
| Strong wind | 29.6 | $511K | ||
| Winter weather | 66.3 | $198K | ||
| Heat wave | 21.0 | $119K | ||
| Lightning | 18.6 | $112K | ||
| Ice storm | 42.7 | $107K | ||
| Earthquake | 9.8 | $17K | ||
| Wildfire | 12.7 | $7K | ||
| Landslide | 14.2 | $98 |
Scores are percentiles: a score of 90 means higher risk than about 90% of US counties for that hazard. Hazards FEMA does not rate here are left out. Social vulnerability is very low and community resilience is very high in FEMA's measures.
Federal disaster history
Recent disasters nationwide ›Declarations by decade
Federal declarations for natural events that included O'Brien County. 2020s bar runs to November 2026.
By type
Most recent
Show all 13
Iowa also had 11 statewide declarations that did not name single counties.
Storm history since 1951
Tornado risk by county ›The National Weather Service has logged 487 storm reports in O'Brien County since 1951, with 0 deaths and 2 injuries and about $25.5 million in reported damage. The strongest on record here was an F3 tornado on October 1, 1971.
Strongest tornadoes
| Date | Strength | Near | Hurt / killed |
|---|---|---|---|
| Oct 1, 1971 | F3 | – | 0 / 0 |
| May 31, 1971 | F3 | – | 0 / 0 |
| Jul 19, 1980 | F2 | – | 0 / 0 |
| Jun 11, 2008 | EF2 | Calumet | 0 / 0 |
| Apr 3, 1968 | F2 | – | 0 / 0 |
Most damaging storms
| Date | Type | Near | Damage |
|---|---|---|---|
| Jul 13, 2004 | Hail | Sheldon | $10M |
| Jul 19, 1980 | Tornado | – | $3M |
| Jun 21, 2024 | Flood | Germantown | $2M |
| Oct 1, 2002 | Hail | Archer | $2M |
| Jul 9, 2009 | Hail | Sheldon | $2M |
| Jun 1, 2019 | Flood | Linn Grove | $1M |
Source: NOAA Storm Events Database, county-based reports through Jul 4, 2026. Tornado records start in 1950, hail and wind in 1955, and floods and other storm types in 1996, so older decades undercount. Damage is in dollars of the year it happened and is often an estimate. Winter storms, heat and hurricanes are logged by forecast zone, not county, so they are not counted here.
Flood insurance in O'Brien County
Check your address flood zone ›National Flood Insurance Program (NFIP) records only; private flood policies are not included. Home counts as of Aug 3, 2026. Since 2021 NFIP prices each home separately under Risk Rating 2.0, so your price depends on the building, not the county. Ask an agent for a quote.
Homes in O'Brien County
Older homes and mobile homes usually suffer more damage in storms, floods and earthquakes, and can cost more to insure. If you are buying, ask about roof age, foundation bolting and any retrofits. Source: US Census Bureau, American Community Survey 2020 to 2024 5-year estimates; 6,564 housing units.
Compare in Iowa
All 99 ›| Largest counties | Overall risk | Top hazard |
|---|---|---|
| Polk County | Inland flooding | |
| Linn County | Inland flooding | |
| Scott County | Inland flooding | |
| Johnson County | Tornado | |
| Black Hawk County | Inland flooding | |
| Woodbury County | Inland flooding | |
| Dallas County | Inland flooding | |
| Dubuque County | Inland flooding |
Neighboring counties
| County | Overall risk | Declarations |
|---|---|---|
| Sioux County | 13 | |
| Plymouth County | 14 | |
| Buena Vista County | 20 | |
| Dickinson County | 16 | |
| Clay County | 19 | |
| Lyon County | 14 | |
| Cherokee County | 21 | |
| Osceola County | 13 |
Common questions about O'Brien County
What is the biggest natural hazard in O'Brien County?
Inland flooding has the highest expected yearly losses in O'Brien County, about $3.9 million a year in FEMA's estimate. Tornado is second at $2.1 million.
How many federal disasters has O'Brien County had?
O'Brien County has been included in 13 federal disaster or emergency declarations for natural events since 1965, including 11 major disasters. The most recent was Severe Storms, Flooding, Straight-Line Winds, and Tornadoes in June 2024.
Is O'Brien County a high-risk place to live?
Its overall rating is Very Low, 91st highest of 99 in Iowa. A county rating covers the whole area. Risk at one address can be much higher or lower, so check the FEMA flood map and ask about the home's history.
Do I need flood insurance in O'Brien County?
Standard home insurance does not cover flooding. About 1 in 1000 homes in O'Brien County has federal flood insurance. Lenders require it in mapped high-risk zones, but many flood claims come from outside those zones.
How many tornadoes has O'Brien County had?
NOAA records list 35 tornadoes in O'Brien County since 1950. The strongest was an F3 tornado on October 1, 1971. The weather service has also logged 209 hail reports and 70 floods here.
Sources: FEMA National Risk Index (December 2025), OpenFEMA Disaster Declarations Summaries, and NFIP policy and claims data. Hazard Compass is independent and not affiliated with FEMA. These figures describe the whole county, not a single property, and are not insurance or safety advice. Report a problem.