Jefferson County, Idaho: Natural Disaster Risk and History
Jefferson County, Idaho has a Very Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 40.1 out of 100, higher than about 40% of US counties, with winter storms, cold waves and earthquakes scoring highest of its 18 hazards and $17 million a year in expected losses.
OpenFEMA lists 4 federal disaster declarations that included Jefferson County since 1976, not counting 2 for COVID-19; the latest is DR-4310-ID (Severe Winter Storms and Flooding, declared 21 April 2017). NOAA's Storm Prediction Center recorded 19 tornadoes touching Jefferson County from 1950 to 2025.
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Population 30,825 Buildings worth $6.2 billion Area 1,117 sq mi Risk rank in Idaho 21 of 44 FIPS 16051
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Winter weather | Relatively Moderate | 82.7 | $328,961 | about 14 a year | 260 |
| Cold wave | Relatively Moderate | 81.8 | $5.6 million | about 2.6 a year | 49 |
| Earthquake | Relatively Low | 80.6 | $2.4 million | about once every 84 years | — |
| Heat wave | Relatively Moderate | 79.1 | $2.0 million | about 1.9 a year | 32 |
| Wildfire | Very Low | 62.5 | $138,109 | about once every 391 years | — |
| Volcanic activity | Very Low | 58.3 | $37 | rarer than once in 1,000 years | 4 |
| Lightning | Relatively Low | 54.7 | $381,074 | about 31 a year | 52,861 strikes |
| Inland flooding | Relatively Low | 37.1 | $6.0 million | about once every 2.5 years | 11 |
| Landslide | Very Low | 34.5 | $596 | about once every 4.5 years | — |
| Drought | Very Low | 22.2 | $9,144 | about 59 a year | 1,785 |
| Hail | Very Low | 20.6 | $100,365 | about once every 2.8 years | 14 |
| Strong wind | Very Low | 12.4 | $133,471 | about once every 1.1 years | 35 |
| Ice storm | Very Low | 10.9 | $7,697 | about once every 67 years | 0 |
| Tornado | Very Low | 7.0 | $47,166 | about once every 8.5 years | 17 |
| Avalanche | Very Low | 1.9 | — | about once every 100 years | 0 |
| Coastal flooding | Not Applicable | — | — | — | — |
| Hurricane | Not Applicable | — | — | — | — |
| Tsunami | 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 4
Most common: Flood 2, Hurricane 1, Severe Storm 1.
| Decade | Declarations | Incident types |
|---|---|---|
| 1970s | 1 | Flood |
| 1990s | 1 | Severe Storm |
| 2000s | 1 | Hurricane |
| 2010s | 1 | Flood |
The last 4
Widest declarations that included Jefferson County
- Hurricane Katrina (2005, EM-3244-ID): 44 Idaho counties designated.
- Severe Storms, Snowmelt, Land/Mud Slides, Flooding (1997, DR-1177-ID): 12 Idaho counties designated.
- Severe Winter Storms and Flooding (2017, DR-4310-ID): 11 Idaho 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. Idaho also had 8 statewide declarations with no county list.
Tornado record since 1950 19
| Tornadoes touching the county | 19 |
|---|---|
| Strongest-rated | (E)F1 ×8 |
| Peak month | June (6) |
| Deadliest | — |
| Longest path | 23 Mar 1988, F1, 15 mi path |
| Most recent | 27 Oct 2025, EF0, 0.1 mi path |
| Deaths / injuries on those paths | 0 / 0 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 11 | 8 | 0 | 0 | 0 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 0 | 0 | 0 | 6 | 5 | 3 | 4 | 1 |
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 | 40.1 | Winter weather |
| Clark County | 52 km | Very Low | 0.8 | Avalanche |
| Madison County | 52 km | Relatively Low | 58.6 | Lightning |
| Bingham County | 67 km | Relatively Low | 60.1 | Winter weather |
| Butte County | 70 km | Very Low | 4.4 | Avalanche |
| Bonneville County | 74 km | Relatively Moderate | 82.4 | Avalanche |
Nearest by distance between county centres. Every county in Idaho, ranked.
Vulnerability and resilience
| Social vulnerability | Very Low 10.6 |
|---|---|
| Community resilience | Relatively Low 39.7 |
| Community risk factor | 0.76 |
| Expected annual loss, all hazards | $17 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 Idaho · all official warnings on Global Incident Tracker.
- Winter weather: Power outages now · Carbon monoxide in winter
- Cold wave: Carbon monoxide in winter · Power outages now
- Earthquake: Earthquakes today · Earthquake safety guide
- 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, Idaho most at risk from?
Jefferson County, Idaho has a Very Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 40.1 out of 100, higher than about 40% of US counties, with winter storms, cold waves and earthquakes scoring highest of its 18 hazards and $17 million a year in expected losses.
How many federal disaster declarations has Jefferson County had?
OpenFEMA lists 4 federal disaster declarations that included Jefferson County since 1976, not counting 2 for COVID-19; the latest is DR-4310-ID (Severe Winter Storms and Flooding, declared 21 April 2017). Another 8 Idaho declarations were made statewide without a county list.
How many tornadoes have hit Jefferson County?
NOAA's Storm Prediction Center recorded 19 tornadoes touching Jefferson County from 1950 to 2025.
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.