Lewis and Clark County, Montana
Natural disaster risk, federal disaster history and flood insurance facts.
Lewis and Clark County, Montana has a relatively low overall risk from natural hazards in FEMA's National Risk Index. Its risk score is higher than 71% of US counties. It ranks 7th of 56 counties in Montana. The costliest hazards here are cold waves, inland flooding and earthquakes. FEMA estimates about $35 million a year in expected losses, or roughly $491 per resident. Since 1975 it has been included in 14 federal disaster or emergency declarations for natural events (6 major disasters). The most recent was in July 2024 (Horse Gulch Fire). Fewer than 1 in 100 homes here carry federal flood insurance (176 policies). Since 1978, federal flood insurance has paid about $432,000 on 102 claims here.
FEMA National Risk Index December 2025; OpenFEMA declarations to Nov 6, 2026; NFIP records. Updated November 6, 2026.
Top risks in Lewis and Clark County
- Insulate pipes in outside walls, crawl spaces and garages.
- Know how to shut off the main water valve.
- 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.
- Ask whether an older house is bolted to its foundation.
- Consider separate earthquake insurance where risk is high.
All 18 hazards
What the ratings mean ›| Hazard | Rating | Score | Expected loss a year | |
|---|---|---|---|---|
| Cold wave | 94.6 | $13M | ||
| Inland flooding | 64.6 | $12M | ||
| Earthquake | 86.8 | $4M | ||
| Wildfire | 92.8 | $3M | ||
| Winter weather | 98.1 | $2M | ||
| Lightning | 66.3 | $504K | ||
| Avalanche | 79.8 | $457K | ||
| Strong wind | 21.2 | $226K | ||
| Heat wave | 35.4 | $213K | ||
| Landslide | 95.2 | $154K | ||
| Tornado | 8.9 | $62K | ||
| Hail | 10.2 | $38K | ||
| Ice storm | 15.7 | $12K | ||
| Drought | 22.8 | $9K |
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 very high in FEMA's measures.
Federal disaster history
Recent disasters nationwide ›Declarations by decade
Federal declarations for natural events that included Lewis and Clark County. 2020s bar runs to November 2026.
By type
Most recent
Show all 14
Montana also had 36 statewide declarations that did not name single counties.
Storm history since 1953
Tornado risk by county ›The National Weather Service has logged 318 storm reports in Lewis and Clark County since 1953, with 0 deaths and 14 injuries and about $5.9 million in reported damage. The strongest on record here was an F0 tornado on June 27, 1997 near Helena.
Strongest tornadoes
| Date | Strength | Near | Hurt / killed |
|---|---|---|---|
| Jun 27, 1997 | F0 | Helena | 0 / 0 |
| Jul 22, 1960 | F0 | – | 0 / 0 |
| Jul 9, 1992 | F0 | – | 0 / 0 |
| Jun 7, 1953 | n/a | – | 0 / 0 |
Most damaging storms
| Date | Type | Near | Damage |
|---|---|---|---|
| Jul 23, 2000 | Wildfire | Helena | $3M |
| Aug 1, 2000 | Wildfire | Helena | $3M |
| Jul 3, 2022 | Flash Flood | Helena | $700K |
| Apr 9, 2023 | Flood | Birdseye | $100K |
| Jul 20, 2012 | Flash Flood | Ft Harrison | $50K |
| Jul 31, 2025 | Debris Flow | Canyon Ferry | $11K |
Source: NOAA Storm Events Database, county-based reports through Jul 23, 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 Lewis and Clark 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 Lewis and Clark 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; 34,082 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 |
|---|---|---|
| Flathead County | 13 | |
| Cascade County | 5 | |
| Jefferson County | 9 | |
| Powell County | 15 | |
| Broadwater County | 10 | |
| Teton County | 10 | |
| Meagher County | 8 |
Cities in Lewis and Clark County
Common questions about Lewis and Clark County
What is the biggest natural hazard in Lewis and Clark County?
Cold wave has the highest expected yearly losses in Lewis and Clark County, about $12.9 million a year in FEMA's estimate. Inland flooding is second at $12.4 million.
How many federal disasters has Lewis and Clark County had?
Lewis and Clark County has been included in 14 federal disaster or emergency declarations for natural events since 1975, including 6 major disasters. The most recent was Horse Gulch Fire in July 2024.
Is Lewis and Clark County a high-risk place to live?
Its overall rating is Relatively Low, 7th 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 Lewis and Clark County?
Standard home insurance does not cover flooding. About 1 in 167 homes in Lewis and Clark 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 Lewis and Clark County had?
NOAA records list 4 tornadoes in Lewis and Clark County since 1950. The strongest was an F0 tornado on June 27, 1997 near Helena. The weather service has also logged 118 hail reports and 39 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.