Big Horn County, Montana: Natural Disaster Risk and History
Big Horn County, Montana has a Relatively Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 57.2 out of 100, higher than about 57% of US counties, with strong winds, wildfires and winter storms scoring highest of its 18 hazards and $11 million a year in expected losses.
OpenFEMA lists 7 federal disaster declarations that included Big Horn County since 1978, not counting 2 for COVID-19; the latest is DR-4902-MT (Severe Winter Storm and Straight-Line Winds, declared 7 April 2026). NOAA's Storm Prediction Center recorded 11 tornadoes touching Big Horn County from 1950 to 2025.
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Population 13,034 Buildings worth $3.5 billion Area 5,067 sq mi Risk rank in Montana 13 of 56 FIPS 30003
All 18 hazards, highest risk first
FEMA National Risk Index| Hazard | Risk rating | Score | Expected loss a year | How often | Events in record |
|---|---|---|---|---|---|
| Strong wind | Relatively High | 95.9 | $1.9 million | about once every 1.2 years | 32 |
| Wildfire | Relatively Moderate | 94.8 | $2.0 million | about once every 162 years | — |
| Winter weather | Relatively High | 88.5 | $211,885 | about 24 a year | 465 |
| Lightning | Relatively High | 83.2 | $493,061 | about 32 a year | 90,032 strikes |
| Cold wave | Relatively Moderate | 76.9 | $1.8 million | about 3.2 a year | 60 |
| Landslide | Relatively Low | 73.8 | $4,902 | about 5.2 a year | — |
| Inland flooding | Relatively Low | 55.1 | $4.5 million | about once every 1.5 years | 19 |
| Hail | Relatively Low | 51.8 | $163,565 | about 1.6 a year | 60 |
| Earthquake | Very Low | 39.6 | $86,041 | rarer than once in 1,000 years | — |
| Drought | Relatively Low | 38.5 | $33,639 | about 75 a year | 2,394 |
| Avalanche | Very Low | 36.3 | $101 | about once every 100 years | 0 |
| Heat wave | Very Low | 34.9 | $103,121 | about 2 a year | 23 |
| Ice storm | Very Low | 12.5 | $4,008 | about once every 67 years | 0 |
| Tornado | Very Low | 12.1 | $54,008 | about once every 3.1 years | 7 |
| Volcanic activity | Very Low | 9.4 | — | rarer than once in 1,000 years | 1 |
| 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 7
Most common: Fire 2, Severe Storm 2, Straight-Line Winds 1, Hurricane 1.
| Decade | Declarations | Incident types |
|---|---|---|
| 1970s | 1 | Flood |
| 2000s | 3 | Hurricane, Severe Storm, Fire |
| 2010s | 1 | Severe Storm |
| 2020s | 2 | Straight-Line Winds, Fire |
The last 7
Widest declarations that included Big Horn County
- Hurricane Katrina Evacuation (2005, EM-3253-MT): 56 Montana counties designated.
- Severe Storms and Flooding (2011, DR-1996-MT): 49 Montana counties designated.
- Wildfires (2000, DR-1340-MT): 48 Montana 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. Montana also had 18 statewide declarations with no county list.
Tornado record since 1950 11
| Tornadoes touching the county | 11 |
|---|---|
| Strongest-rated | (E)F1 ×6 |
| Peak month | June (7) |
| Deadliest | — |
| Longest path | 22 Jun 1996, F1, 4 mi path |
| Most recent | 7 Jun 2018, EF1, 0.8 mi path |
| Deaths / injuries on those paths | 0 / 0 |
| Rating | (E)F0 | (E)F1 | (E)F2 | (E)F3 | (E)F4 | (E)F5 | Unrated |
|---|---|---|---|---|---|---|---|
| Count | 5 | 6 | 0 | 0 | 0 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 0 | 2 | 1 | 2 | 5 | 0 | 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 Big Horn County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| Big Horn County (this page) | — | Relatively Low | 57.2 | Strong wind |
| Yellowstone County | 83 km | Relatively Moderate | 83.6 | Winter weather |
| Sheridan County, WY | 85 km | Relatively Low | 65.2 | Wildfire |
| Treasure County | 89 km | Very Low | 0.5 | Wildfire |
| Big Horn County, WY | 107 km | Very Low | 31.1 | Landslide |
| Rosebud County | 108 km | Relatively Low | 49.7 | Wildfire |
Nearest by distance between county centres. Every county in Montana, ranked.
Vulnerability and resilience
| Social vulnerability | Very High 94.1 |
|---|---|
| Community resilience | Very Low 4.8 |
| Community risk factor | 1.80 |
| Expected annual loss, all hazards | $11 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 Big Horn County's main hazards
- Right now: National Weather Service alerts for Montana · all official warnings on Global Incident Tracker.
- Strong wind: Power outages now
- Wildfire: US wildfires now · Wildfire smoke: what protects you
- Winter weather: Power outages now · Carbon monoxide in winter
- 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 Big Horn County
What natural disasters is Big Horn County, Montana most at risk from?
Big Horn County, Montana has a Relatively Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 57.2 out of 100, higher than about 57% of US counties, with strong winds, wildfires and winter storms scoring highest of its 18 hazards and $11 million a year in expected losses.
How many federal disaster declarations has Big Horn County had?
OpenFEMA lists 7 federal disaster declarations that included Big Horn County since 1978, not counting 2 for COVID-19; the latest is DR-4902-MT (Severe Winter Storm and Straight-Line Winds, declared 7 April 2026). Another 18 Montana declarations were made statewide without a county list.
How many tornadoes have hit Big Horn County?
NOAA's Storm Prediction Center recorded 11 tornadoes touching Big Horn 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.