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Lewis and Clark County, Montana severe weather history spans 314 recorded events between 1953 and 2025. The dominant hazard is hail, accounting for 36.6% of all recorded events. It ranks #1,702 nationally and #22 in Montana.
314
Recorded events
0
Direct deaths
14
Direct injuries
$5.9M
Property damage
The record
What the Lewis and Clark County, Montana severe weather history record shows
Across the archive, Lewis and Clark County, Montana severe weather history averages 4.4 recorded events a year. The busiest stretch on record is the 2000s, with 102 events logged in that decade alone. Roughly 40 events fall before 1990 and 274 from 1990 onward — a gap that reflects the expansion of NOAA reporting practice as much as the weather itself.
The costliest is wildfire, with $5.0M in reported property damage. In total, 11 distinct hazard types appear in this county archive, each listed with its own dated record below.
By hazard type
Every hazard type recorded in Lewis and Clark County
| Hazard | Events | Deaths | Damage | Max | Span |
|---|---|---|---|---|---|
| Hail | 115 | 0 | $2K | 3 | 1955–2024 |
| Thunderstorm Wind | 114 | 0 | $21K | 76 | 1974–2025 |
| Heavy Rain | 29 | 0 | $0 | 0 | 2019–2022 |
| Flash Flood | 21 | 0 | $759K | 0 | 1999–2024 |
| Flood | 18 | 0 | $100K | 0 | 2008–2023 |
| Wildfire | 5 | 0 | $5.0M | 0 | 2000–2000 |
| Tornado | 4 | 0 | $2K | F0 | 1953–1997 |
| Debris Flow | 3 | 0 | $21K | 0 | 2012–2025 |
| Lightning | 3 | 0 | $0 | 0 | 2003–2023 |
| Funnel Cloud | 1 | 0 | $0 | 0 | 1996–1996 |
| Dust Devil | 1 | 0 | $1K | 0 | 2008–2008 |
Decade by decade
Lewis and Clark County, Montana severe weather history by decade
Reporting practice changed over time — early decades are undercounted, not calmer.
Tornado tracks
Paths crossing this county
7 mapped tornado paths intersect this county: 7 touched down inside it and 0 crossed in from a neighbouring county. This comes from path geometry, not county-tagged reports.
| Date | Scale | Deaths | Injuries | Path length | Origin |
|---|---|---|---|---|---|
| 1966-07-02 | EF2 | 0 | 0 | 0.8 mi | Touched down here |
| 1997-06-27 | EF0 | 0 | 0 | 0.1 mi | Touched down here |
| 1993-06-11 | EF0 | 0 | 0 | 0.1 mi | Touched down here |
| 1993-06-21 | EF0 | 0 | 0 | 0.1 mi | Touched down here |
| 1992-07-09 | EF0 | 0 | 0 | 0.1 mi | Touched down here |
| 1960-07-22 | EF0 | 0 | 0 | 1.0 mi | Touched down here |
| 1953-06-07 | EF0 | 0 | 0 | 0.1 mi | Touched down here |
Significant events
Deadliest events on record in Lewis and Clark County
| Date | Type | Location | Deaths | Injuries | Damage |
|---|---|---|---|---|---|
| Aug 13, 2003 | Lightning | CRAIG | 0 | 5 | $0 |
| Jun 18, 2022 | Lightning | GILMAN | 0 | 3 | $0 |
| Jun 12, 2023 | Lightning | (HLN)HELENA RGNL ARP | 0 | 2 | $0 |
| Aug 1, 2000 | Wildfire | HELENA | 0 | 2 | $2.5M |
| Jul 23, 2000 | Wildfire | HELENA | 0 | 2 | $2.5M |
From the record
What the reports say
Written by National Weather Service staff at the time of the event · public domain
Significant flash flooding across downtown and Last Chance Gulch area. Severe businesses sustained damage, including Helena YWCA and the Lewis and Clark Library. 1 to 2 feet of water flowing up against business doors. Flood waters up to bumpers of vans. Moviegoers at the Helena Cinemark report the movie theater being evacuated, with water draining into the lobby area. Some vehicles were also initially stranded in the lower level of the Great Northern Parking Garage. Several streets in the Capitol area saw rapid flooding with a number of homeowners reporting basement flooding.
Lewis and Clark County Sheriff's Office reported the high bridge over the Dearborn River was washed out. Public works closed the road at Flat Creek. Several secondary roads across the area were flooded at times. Flooding across northwest Helena also occurred, especially west of Birdseye Road.
Jimtown Road and the Riverside Campground was closed due to debris flow from the burn scar flooding. Media also reported a 15 foot debris flow caused by the flooding washed away two trucks and a shed to the shores of Canyon Ferry Lake.
Context
Risk, population and federal disasters
Relatively Low
FEMA NRI risk rating
73,464
Population (ACS)
$394K
Median home value
16
Federal declarations
| Declared | Incident | Title | Type |
|---|---|---|---|
| Jul 12, 2024 | Fire | HORSE GULCH FIRE | FM |
| Mar 31, 2020 | Biological | COVID-19 PANDEMIC | DR |
| Mar 13, 2020 | Biological | COVID-19 | EM |
| Jul 28, 2019 | Fire | NORTH HILLS FIRE | FM |
| Oct 31, 2018 | Flood | FLOODING | DR |
| Sep 9, 2017 | Fire | ALICE CREEK FIRE | FM |
Quick answers
Frequently asked
How many severe weather events have been recorded in Lewis and Clark County, Montana?
314 events are on record between 1953 and 2025, causing 0 direct deaths and $5.9M in property damage.
What is the most common severe weather hazard in Lewis and Clark County?
Hail, with 115 recorded events — 36.6% of everything in the archive for this county.
How many tornadoes have crossed Lewis and Clark County?
7 mapped tornado paths intersect the county boundary; 7 of them touched down inside it. This is derived from path geometry, not county-tagged reports.
How many federal disaster declarations cover Lewis and Clark County?
16 federal disaster declarations from FEMA include Lewis and Clark County, each tied to a specific incident period.
How risky is Lewis and Clark County compared with the rest of the country?
FEMA's National Risk Index rates Lewis and Clark County as relatively low risk, placing it in the 71 percentile of its state for expected annual loss.
Where does the Lewis and Clark County, Montana severe weather history data come from?
Every figure is drawn from United States federal public-domain records: NOAA/NCEI Storm Events for the event archive, NOAA SPC SVRGIS for mapped tornado paths, FEMA for disaster declarations and risk ratings, and the U.S. Census for population context. Dates are shown in UTC and recent entries may still be revised by NOAA.
Nearby
Neighbouring counties
- Lake County 111
- Liberty County 143
- Judith Basin County 247
- Lincoln County 70
- Jefferson County 102
- McCone County 479
Cite this page
“Lewis and Clark County, Montana.” Severe Weather History. severeweatherhistory.com/county/montana/lewis-and-clark-county/ · Data: NOAA/NCEI, FEMA, U.S. Census — public domain.