Jefferson County, Montana Natural Disaster Risk
FEMA National Risk Index assessment · MT
Very LowComposite Risk Score
National percentile: 22th
Jefferson County faces very low composite natural disaster risk (NRI Risk Index score 21.6, 22th national percentile), driven primarily by landslide and wildfire exposure. Expected annual loss across all 18 hazard types is $9M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Jefferson County at very low composite risk, with a National Risk Index score of 21.6 out of 100 — placing it in the 22nd national percentile and among the lowest-risk counties in the country. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Risk here concentrates in landslide (downhill movement of rock, soil, and debris on unstable slopes) at Medium risk — $185K in expected annual loss and about 1.24 events per year; wildfire (uncontrolled fires that spread across wildland and into communities) at Medium risk — $1M in expected annual loss and about 0.00 events per year; and winter weather (heavy snow, blizzards, and hazardous winter conditions) at Medium risk — $213K in expected annual loss and about 33.89 events per year. Across all hazards, FEMA estimates $9M in expected annual loss for a population of 12K.
Beyond physical exposure, Jefferson County has a low social vulnerability rating (how susceptible the population is to harm) and a low community resilience rating (its capacity to prepare for and recover from disasters). Both measures sit toward the lower end, indicating relatively modest population sensitivity.
History supports the rating: Jefferson County has received 11 federal disaster declarations since 1975, including 3 for flood events and 3 for fire events. The most recent was Covid-19 Pandemic (biological), declared in March 2020.
Among 56 Montana counties, Jefferson County ranks #30 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Landslide | Medium | 1.24 / yr | $185K |
| Wildfire | Medium | 0.00 / yr | $1M |
| Winter Weather | Medium | 33.89 / yr | $213K |
| Earthquake | Low | 0.02 / yr | $672K |
| Cold Wave | Low | 4.21 / yr | $2M |
| Lightning | Medium | 34.48 / yr | $358K |
| Riverine Flood | Very Low | 0.18 / yr | $4M |
| Drought | Very Low | 84.13 / yr | $4K |
| Hail | Very Low | 0.67 / yr | $78K |
| Avalanche | Very Low | 0.01 / yr | $23 |
| Heat Wave | Very Low | 0.45 / yr | $21K |
| Strong Wind | Very Low | 0.39 / yr | $56K |
| Ice Storm | Very Low | 0.01 / yr | $4K |
| Tornado | Very Low | 0.05 / yr | $27K |
| Coastal Flood | Very Low | 0.00 / yr | $0 |
| Hurricane | Very Low | 0.00 / yr | $0 |
| Tsunami | Very Low | 0.00 / yr | $0 |
| Volcanic Activity | Very Low | 0.00 / yr | $0 |
Disaster History
Jefferson County has received 11 federal disaster declarations since 1975, most recently Covid-19 Pandemic in March 2020. Most frequent causes: Flood (3), Fire (3), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| April 2014 | Flood | Ice Jams and Flooding |
| August 2012 | Fire | Nineteen Mile Fire |
| June 2011 | Severe Storm | Severe Storms and Flooding |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
| August 2000 | Fire | Wildfires |
| July 2000 | Fire | Mt - Central Zone 3b Fire Complex |
| February 1996 | Severe Storm | Severe Storms, Flooding, and Ice Jams |
| May 1981 | Flood | Severe Storms & Flooding |
Showing the 10 most recent of 11 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Jefferson County?
Jefferson County has a composite FEMA National Risk Index score of 21.6 out of 100, placing it in the Very Low category and the 22th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Jefferson County?
The three highest-rated hazards are Landslide (Medium, $185K EAL), Wildfire (Medium, $1M EAL), Winter Weather (Medium, $213K EAL). These account for most of the county's expected annual losses.
How does Jefferson County compare to other Montana counties?
Jefferson County ranks #30 of 56 Montana counties for overall natural disaster risk, with a very low rating.
How many federally declared disasters has Jefferson County had?
FEMA records 11 federal disaster declarations for Jefferson County since 1975, most often 3 for flood events and 3 for fire events. The most recent was Covid-19 Pandemic, declared in March 2020.
What does Expected Annual Loss (EAL) mean?
EAL is FEMA's estimate of average annual dollar losses from natural hazards, calculated from historical event data and exposure models. Jefferson County's $9M EAL is a statistical average, not a guarantee for any specific year or address.