Lewis and Clark County, Montana: Natural Disaster Risk and History
Lewis and Clark County, Montana has a Relatively Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 71.2 out of 100, higher than about 71% of US counties, with winter storms, landslides and cold waves scoring highest of its 18 hazards and $35 million a year in expected losses.
OpenFEMA lists 14 federal disaster declarations that included Lewis and Clark County since 1975, not counting 2 for COVID-19; the latest is FM-5507-MT (Horse Gulch Fire, declared 12 July 2024). NOAA's Storm Prediction Center recorded 6 tornadoes touching Lewis and Clark County from 1950 to 2025.
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Population 70,922 Buildings worth $16 billion Area 3,533 sq mi Risk rank in Montana 7 of 56 FIPS 30049
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 | Very High | 98.1 | $1.6 million | about 44 a year | 832 |
| Landslide | Relatively Moderate | 95.2 | $154,163 | about 2.2 a year | — |
| Cold wave | Relatively High | 94.6 | $13 million | about 6.3 a year | 120 |
| Wildfire | Relatively Moderate | 92.8 | $2.5 million | about once every 424 years | — |
| Earthquake | Relatively Low | 86.8 | $3.8 million | about once every 137 years | — |
| Avalanche | Relatively Moderate | 79.8 | $456,670 | about once every 30 years | 1 |
| Lightning | Relatively Moderate | 66.3 | $504,410 | about 25 a year | 126,092 strikes |
| Inland flooding | Relatively Low | 64.6 | $12 million | about 1.1 a year | 30 |
| Heat wave | Very Low | 35.4 | $213,047 | about once every 1.4 years | 14 |
| Drought | Very Low | 22.8 | $9,009 | about 76 a year | 2,646 |
| Strong wind | Relatively Low | 21.2 | $225,718 | about once every 1.9 years | 20 |
| Ice storm | Very Low | 15.7 | $11,961 | about once every 67 years | 0 |
| Hail | Very Low | 10.2 | $38,203 | about once every 1.3 years | 30 |
| Tornado | Very Low | 8.9 | $62,292 | about once every 13 years | 5 |
| Coastal flooding | Not Applicable | — | — | — | — |
| Hurricane | Not Applicable | — | — | — | — |
| Tsunami | Not Applicable | — | — | — | — |
| Volcanic activity | 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 14
Most common: Fire 8, Flood 3, Severe Storm 2, Hurricane 1.
| Decade | Declarations | Incident types |
|---|---|---|
| 1970s | 1 | Flood |
| 1980s | 1 | Flood |
| 1990s | 1 | Severe Storm |
| 2000s | 5 | Fire ×4, Hurricane |
| 2010s | 5 | Fire ×3, Flood, Severe Storm |
| 2020s | 1 | Fire |
The last 10
Widest declarations that included Lewis and Clark 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 6
| Tornadoes touching the county | 6 |
|---|---|
| Strongest-rated | (E)F0 ×6 |
| Peak month | June (4) |
| Deadliest | — |
| Longest path | 22 Jul 1960, F0, 1 mi path |
| Most recent | 27 Jun 1997, F0, 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 | 6 | 0 | 0 | 0 | 0 | 0 | 0 |
| Decade | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020s |
|---|---|---|---|---|---|---|---|---|
| Count | 1 | 1 | 0 | 0 | 4 | 0 | 0 | 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 Lewis and Clark County compares with its 5 nearest counties
| County | Distance | Overall risk | Score | Top hazard |
|---|---|---|---|---|
| Lewis and Clark County (this page) | — | Relatively Low | 71.2 | Winter weather |
| Powell County | 51 km | Very Low | 10.0 | Landslide |
| Teton County | 80 km | Very Low | 19.0 | Avalanche |
| Cascade County | 82 km | Relatively Moderate | 83.1 | Winter weather |
| Jefferson County | 111 km | Very Low | 21.6 | Landslide |
| Broadwater County | 111 km | Very Low | 17.7 | Landslide |
Nearest by distance between county centres. Every county in Montana, ranked.
Vulnerability and resilience
| Social vulnerability | Relatively Low 21.2 |
|---|---|
| Community resilience | Very High 83.3 |
| Community risk factor | 0.89 |
| Expected annual loss, all hazards | $35 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 Lewis and Clark County's main hazards
- Right now: National Weather Service alerts for Montana · all official warnings on Global Incident Tracker.
- Winter weather: Power outages now · Carbon monoxide in winter
- Landslide: Landslides recorded
- Cold wave: Carbon monoxide in winter · Power outages now
- 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 Lewis and Clark County
What natural disasters is Lewis and Clark County, Montana most at risk from?
Lewis and Clark County, Montana has a Relatively Low natural-hazard risk rating in FEMA's National Risk Index (v1.20, December 2025): a score of 71.2 out of 100, higher than about 71% of US counties, with winter storms, landslides and cold waves scoring highest of its 18 hazards and $35 million a year in expected losses.
How many federal disaster declarations has Lewis and Clark County had?
OpenFEMA lists 14 federal disaster declarations that included Lewis and Clark County since 1975, not counting 2 for COVID-19; the latest is FM-5507-MT (Horse Gulch Fire, declared 12 July 2024). Another 18 Montana declarations were made statewide without a county list.
How many tornadoes have hit Lewis and Clark County?
NOAA's Storm Prediction Center recorded 6 tornadoes touching Lewis and Clark 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.