Lewis and Clark County, Montana Natural Disaster Risk
FEMA National Risk Index assessment · MT
LowComposite Risk Score
National percentile: 71th
Lewis and Clark County faces low composite natural disaster risk (NRI Risk Index score 71.2, 71th national percentile), driven primarily by winter weather and landslide exposure. Expected annual loss across all 18 hazard types is $35M.
Source: FEMA National Risk Index v1.20 · Updated December 2025
Risk Overview
FEMA's National Risk Index rates Lewis and Clark County at low composite risk, with a National Risk Index score of 71.2 out of 100 — placing it in the 71st national percentile and below the national average for natural-disaster risk. The score blends Expected Annual Loss, Social Vulnerability, and Community Resilience across all 18 FEMA hazard types.
Most of Lewis and Clark County's expected losses come from winter weather (heavy snow, blizzards, and hazardous winter conditions) at Very High risk — $2M in expected annual loss and about 43.82 events per year; landslide (downhill movement of rock, soil, and debris on unstable slopes) at Medium risk — $154K in expected annual loss and about 2.20 events per year; and cold wave (prolonged spells of dangerously low temperatures) at High risk — $13M in expected annual loss and about 6.33 events per year. Across all hazards, FEMA estimates $35M in expected annual loss for a population of 71K.
Beyond physical exposure, Lewis and Clark County has a low social vulnerability rating (how susceptible the population is to harm) and a very high community resilience rating (its capacity to prepare for and recover from disasters). A less vulnerable population paired with strong resilience helps the community absorb and recover from events.
The county's disaster history tells the same story: Lewis and Clark County has received 16 federal disaster declarations since 1975, including 8 for fire events and 3 for flood events. The most recent was Horse Gulch Fire (fire), declared in July 2024.
Among 56 Montana counties, Lewis and Clark County ranks #7 for overall natural disaster risk.
Top Hazards
All 18 Hazard Risks
| Winter Weather | Very High | 43.82 / yr | $2M |
| Landslide | Medium | 2.20 / yr | $154K |
| Cold Wave | High | 6.33 / yr | $13M |
| Wildfire | Medium | 0.00 / yr | $3M |
| Earthquake | Low | 0.01 / yr | $4M |
| Avalanche | Medium | 0.03 / yr | $457K |
| Lightning | Medium | 24.56 / yr | $504K |
| Riverine Flood | Low | 1.07 / yr | $12M |
| Heat Wave | Very Low | 0.70 / yr | $213K |
| Drought | Very Low | 76.10 / yr | $9K |
| Strong Wind | Low | 0.51 / yr | $226K |
| Ice Storm | Very Low | 0.01 / yr | $12K |
| Hail | Very Low | 0.77 / yr | $38K |
| Tornado | Very Low | 0.08 / yr | $62K |
| 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
Lewis and Clark County has received 16 federal disaster declarations since 1975, most recently Horse Gulch Fire in July 2024. Most frequent causes: Fire (8), Flood (3), Biological (2).
| Declared | Type | Disaster |
|---|---|---|
| July 2024 | Fire | Horse Gulch Fire |
| March 2020 | Biological | Covid-19 Pandemic |
| March 2020 | Biological | Covid-19 |
| July 2019 | Fire | North Hills Fire |
| October 2018 | Flood | Flooding |
| September 2017 | Fire | Alice Creek Fire |
| June 2012 | Fire | Corral Fire |
| June 2011 | Severe Storm | Severe Storms and Flooding |
| September 2007 | Fire | Country Club Fire |
| September 2005 | Hurricane | Hurricane Katrina Evacuation |
Showing the 10 most recent of 16 declarations.
Source: FEMA Disaster Declarations Summaries (OpenFEMA).
Frequently Asked Questions
What is the overall natural disaster risk for Lewis and Clark County?
Lewis and Clark County has a composite FEMA National Risk Index score of 71.2 out of 100, placing it in the Low category and the 71th national percentile. This combines Expected Annual Loss, Social Vulnerability, and Community Resilience across 18 hazard types.
What are the top natural hazards in Lewis and Clark County?
The three highest-rated hazards are Winter Weather (Very High, $2M EAL), Landslide (Medium, $154K EAL), Cold Wave (High, $13M EAL). These account for most of the county's expected annual losses.
How does Lewis and Clark County compare to other Montana counties?
Lewis and Clark County ranks #7 of 56 Montana counties for overall natural disaster risk, with a low rating.
How many federally declared disasters has Lewis and Clark County had?
FEMA records 16 federal disaster declarations for Lewis and Clark County since 1975, most often 8 for fire events and 3 for flood events. The most recent was Horse Gulch Fire, declared in July 2024.
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. Lewis and Clark County's $35M EAL is a statistical average, not a guarantee for any specific year or address.