Jefferson County, Iowa: Natural Disaster Risk and History
Jefferson County, Iowa has a Very Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 27.1 out of 100, higher than about 27% of US counties, with drought, heat waves and hail scoring highest of its 18 hazards and $7.5 million a year in expected losses.
OpenFEMA lists 10 federal disaster declarations that included Jefferson County since 1965, not counting 2 for COVID-19; the latest is DR-4234-IA (Severe Storms, Tornadoes, Straight-Line Winds, and Flooding, declared 31 July 2015). NOAA's Storm Prediction Center recorded 13 tornadoes touching Jefferson County from 1950 to 2025.
Live weather alerts for Iowa All official warnings Latest FEMA declarations
Population 15,635 Buildings worth $4.5 billion Area 441 sq mi Risk rank in Iowa 73 of 99 FIPS 19101
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Drought | Relatively Moderate | 82.3 | $899,750 | about 14 a year | 434 |
| Heat wave | Relatively Moderate | 79.5 | $1.2 million | about 8.9 a year | 133 |
| Hail | Relatively Moderate | 75.3 | $591,975 | about 4 a year | 152 |
| Lightning | Relatively Moderate | 67.6 | $379,770 | about 45 a year | 65,683 strikes |
| Strong wind | Relatively Moderate | 59.9 | $612,640 | about 5.2 a year | 198 |
| Landslide | Very Low | 58.3 | $2,019 | about once every 7.1 years | — |
| Wildfire | Very Low | 54.7 | $51,655 | rarer than once in 1,000 years | — |
| Tornado | Relatively Low | 54.1 | $1.2 million | about once every 3.1 years | 17 |
| Winter weather | Relatively Low | 41.4 | $40,016 | about 12 a year | 231 |
| Ice storm | Relatively Low | 39.2 | $42,676 | about once every 2.8 years | 25 |
| Earthquake | Very Low | 38.1 | $114,207 | about once every 1,000 years | — |
| Cold wave | Relatively Low | 24.4 | $260,643 | about 5.3 a year | 101 |
| Inland flooding | Very Low | 20.4 | $2.1 million | about once every 1.5 years | 19 |
| Hurricane | Very Low | 13.1 | $2,585 | about once every 135 years | 0 |
| Avalanche | Not Applicable | — | — | — | — |
| Coastal flooding | Not Applicable | — | — | — | — |
| Tsunami | Not Applicable | — | — | — | — |
| Volcanic activity | Not Applicable | — | — | — | — |
Score: FEMA's percentile among US counties that face the hazard (higher = more risk). Expected loss: FEMA's modelled average yearly loss to buildings, people (as a statistical value) and crops. How often: FEMA's annualised frequency of the hazard in the county; for some hazards it counts event-days, so it is a rough guide, not a forecast. "Not Applicable" means FEMA does not model that hazard here.
Federal disaster declarations 10
Most common: Flood 6, Severe Storm 2, Severe Ice Storm 1, Hurricane 1.
| Decade | Declarations | Incident types |
|---|---|---|
| 1960s | 2 | Flood ×2 |
| 1970s | 1 | Flood |
| 1990s | 2 | Flood ×2 |
| 2000s | 3 | Severe Ice Storm, Severe Storm, Hurricane |
| 2010s | 2 | Severe Storm, Flood |
The last 10
Widest declarations that included Jefferson County
- Hurricane Katrina Evacuation (2005, EM-3239-IA): 99 Iowa counties designated.
- Severe Storms & Flooding (1993, DR-996-IA): 99 Iowa counties designated.
- Severe Storms, Tornadoes and Flooding (1998, DR-1230-IA): 81 Iowa counties designated.
Named storms in its declarations: Hurricane Katrina (2005).
Not counted above: 2 COVID-19 ("Biological") declarations — in 2020 every US county was included. Iowa also had 7 statewide declarations with no county list.
Tornado record since 1950 13
| Tornadoes touching the county | 13 |
|---|---|
| Strongest-rated | (E)F3 ×2 |
| Peak month | April (5) |
| Deadliest | 9 Nov 1975, F2, 8.8 mi path, 0 killed, 3 injured |
| Longest path | 8 May 1988, F2, 71 mi path |
| Most recent | 17 May 2017, EF1, 3.2 mi path |
| Deaths / injuries on those paths | 0 / 4 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 5 | 3 | 3 | 2 | 0 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 1 | 1 | 1 | 3 | 3 | 3 | 1 | 0 |
Deaths and injuries are for each tornado's whole path, which can run beyond this county. F-scale ratings before February 2007, Enhanced Fujita (EF) after.
How Jefferson County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| Jefferson County (this page) | — | Very Low | 27.1 | Drought |
| Van Buren County | 31 km | Very Low | 33.6 | Drought |
| Henry County | 34 km | Very Low | 30.9 | Heat wave |
| Wapello County | 39 km | Relatively Low | 65.3 | Drought |
| Washington County | 39 km | Relatively Low | 44.2 | Strong wind |
| Keokuk County | 39 km | Very Low | 21.9 | Drought |
Nearest by distance between county centres. Every county in Iowa, ranked.
Vulnerability and resilience
| Social vulnerability | Relatively High 62.3 |
|---|---|
| Community resilience | Relatively Moderate 50.1 |
| Community risk factor | 1.24 |
| Expected annual loss, all hazards | $7.5 million |
FEMA scales expected losses up where social vulnerability is high (people who may find it harder to prepare, evacuate or recover) and down where community resilience is high. A factor above 1 raises the risk score. For social vulnerability a high rating is worse; for resilience a high rating is better.
Prepare for Jefferson County's main hazards
- Right now: National Weather Service alerts for Iowa · all official warnings on Global Incident Tracker.
- Drought: Drought monitor for Iowa
- Heat wave: Heatstroke warning signs
- Hail: Weather alerts for Iowa
- Your property's flood zone: FEMA Flood Map Service Center ↗ — this page cannot tell you that.
- Official preparedness guidance: Ready.gov ↗ and your county emergency management office.
What this page shows, and what it misses
FEMA's National Risk Index rates a whole county against every other US county; it is a planning-level estimate for nationwide comparison, not a flood-zone map and not a substitute for a local risk assessment or the risk to one home. Declarations are presidential disaster, emergency and fire management declarations that named this county; state declarations and SBA or USDA designations are not included. Tornadoes are counted when the county is one of up to four listed on the track; 670 tornadoes that crossed a state line carry no county list in NOAA's file and are left out.
Federal Emergency Management Agency (FEMA), National Risk Index Dataset: National Risk Index Counties - v1.20.0 (December 2025). Retrieved from https://services.arcgis.com/XG15cJAlne2vxtgt/ArcGIS/rest/services/National_Risk_Index_Counties/FeatureServer/0/query on November 2, 2026, 1:20 PM EST. This product uses the Federal Emergency Management Agency’s National Risk Index dataset API or downloadable datasets but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Federal Emergency Management Agency (FEMA), OpenFEMA Dataset: Disaster Declarations Summaries - v2, retrieved from https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries on November 2, 2026, 1:21 PM EST. This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).
Tornado records: NOAA/NWS Storm Prediction Center, Severe Weather Database, tornadoes 1950–2025 (https://www.spc.noaa.gov/wcm/data/1950-2025_actual_tornadoes.csv, downloaded 2 November 2026). Public domain; not endorsed by NOAA. Compiled by Global Incident Tracker.
Questions about Jefferson County
What natural disasters is Jefferson County, Iowa most at risk from?
Jefferson County, Iowa has a Very Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 27.1 out of 100, higher than about 27% of US counties, with drought, heat waves and hail scoring highest of its 18 hazards and $7.5 million a year in expected losses.
How many federal disaster declarations has Jefferson County had?
OpenFEMA lists 10 federal disaster declarations that included Jefferson County since 1965, not counting 2 for COVID-19; the latest is DR-4234-IA (Severe Storms, Tornadoes, Straight-Line Winds, and Flooding, declared 31 July 2015). Another 7 Iowa declarations were made statewide without a county list.
How many tornadoes have hit Jefferson County?
NOAA's Storm Prediction Center recorded 13 tornadoes touching Jefferson County from 1950 to 2025. The deadliest: 9 Nov 1975, F2, 8.8 mi path, 0 killed, 3 injured (deaths and injuries are for the whole path).
Is the National Risk Index a flood zone map?
No. The National Risk Index is a planning-level estimate for a whole county, built for nationwide comparison. It does not tell you the flood zone or the risk of a single property: for that, look up the address on FEMA's Flood Map Service Center (msc.fema.gov) and ask your local floodplain manager.