Jefferson County, Montana
Natural disaster risk, federal disaster history and flood insurance facts.
Jefferson County, Montana has a very low overall risk from natural hazards in FEMA's National Risk Index. Its risk score is lower than 78% of US counties. It ranks 30th of 56 counties in Montana. The costliest hazards here are inland flooding, cold waves and wildfires. FEMA estimates about $8.6 million a year in expected losses, or roughly $711 per resident. Since 1975 it has been included in 9 federal disaster or emergency declarations for natural events (6 major disasters). The most recent was in April 2014 (ice jams and flooding). Only 22 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 Jefferson 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.
- Insulate pipes in outside walls, crawl spaces and garages.
- Know how to shut off the main water valve.
- Clear dry plants and debris within 5 feet of the house.
- Get home insurance quotes early; availability varies by area.
All 18 hazards
What the ratings mean ›| Hazard | Rating | Score | Expected loss a year | |
|---|---|---|---|---|
| Inland flooding | 29.4 | $4M | ||
| Cold wave | 62.7 | $2M | ||
| Wildfire | 89.1 | $1M | ||
| Earthquake | 64.8 | $672K | ||
| Lightning | 59.0 | $358K | ||
| Winter weather | 78.3 | $213K | ||
| Landslide | 95.9 | $185K | ||
| Hail | 19.6 | $78K | ||
| Strong wind | 7.1 | $56K | ||
| Tornado | 5.7 | $27K | ||
| Heat wave | 10.1 | $21K | ||
| Drought | 19.8 | $4K | ||
| Ice storm | 7.0 | $4K | ||
| Avalanche | 16.8 | $23 |
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 relatively low and community resilience is relatively low in FEMA's measures.
Federal disaster history
Recent disasters nationwide ›Declarations by decade
Federal declarations for natural events that included Jefferson County. 2020s bar runs to November 2026.
By type
Most recent
Montana also had 36 statewide declarations that did not name single counties.
Storm history since 1958
Tornado risk by county ›The National Weather Service has logged 103 storm reports in Jefferson County since 1958, with 0 deaths and 2 injuries and about $300,000 in reported damage. The strongest on record here was an EFU tornado on August 6, 2023 near Boulder Arpt.
Strongest tornadoes
| Date | Strength | Near | Hurt / killed |
|---|---|---|---|
| Aug 6, 2023 | EFU | Boulder Arpt | 0 / 0 |
Most damaging storms
| Date | Type | Near | Damage |
|---|---|---|---|
| Jul 2, 1998 | Flash Flood | Cardwell | $100K |
| Jun 27, 2023 | Flash Flood | Cardwell | $100K |
| May 27, 1994 | Thunderstorm Wind | Nr Boulder | $50K |
| Aug 20, 1994 | Thunderstorm Wind | Whitehall | $50K |
Source: NOAA Storm Events Database, county-based reports through Jul 16, 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 Jefferson 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 Jefferson 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; 5,407 housing units.
Compare in Montana
All 56 ›| Largest counties | Overall risk | Top hazard |
|---|---|---|
| Yellowstone County | Inland flooding | |
| Gallatin County | Earthquake | |
| Missoula County | Inland flooding | |
| Flathead County | Inland flooding | |
| Cascade County | Inland flooding | |
| Lewis and Clark County | Cold wave | |
| Ravalli County | Wildfire | |
| Silver Bow County | Cold wave |
Neighboring counties
| County | Overall risk | Declarations |
|---|---|---|
| Gallatin County | 7 | |
| Lewis and Clark County | 14 | |
| Silver Bow County | 5 | |
| Deer Lodge County | 8 | |
| Madison County | 5 | |
| Powell County | 15 | |
| Broadwater County | 10 |
Common questions about Jefferson County
What is the biggest natural hazard in Jefferson County?
Inland flooding has the highest expected yearly losses in Jefferson County, about $3.9 million a year in FEMA's estimate. Cold wave is second at $1.8 million.
How many federal disasters has Jefferson County had?
Jefferson County has been included in 9 federal disaster or emergency declarations for natural events since 1975, including 6 major disasters. The most recent was Ice Jams and Flooding in April 2014.
Is Jefferson County a high-risk place to live?
Its overall rating is Very Low, 30th highest of 56 in Montana. 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 Jefferson County?
Standard home insurance does not cover flooding. About 1 in 333 homes in Jefferson 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 Jefferson County had?
NOAA records list 1 tornadoes in Jefferson County since 1950. The strongest was an EFU tornado on August 6, 2023 near Boulder Arpt. The weather service has also logged 57 hail reports and 7 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.