Lewis and Clark County, Montana
County storm and disaster record · FIPS 30049 · population 70,922 · 3,458 sq mi
NOAA's Storm Events Database holds 1,610 records for Lewis and Clark County, Montana from 1950 through June 30, 2026, on 988 days; the most frequent are high wind and dust records (746 records). 1,293 of them are forecast-zone records, which the National Weather Service files once per zone: a county covered by several zones receives each one, so a single storm can add several records on the same day. The deadliest single record is the April 28, 2019 winter weather, filed for the forecast zone Southern Lewis And Clark, which covers the county: 1 death and 5 injuries. FEMA has issued 16 declarations naming the county since 1975, 14 of them for natural hazards; the latest for a natural hazard was “Horse Gulch Fire” on July 12, 2024.
The record, 1950 to 2026
Storm records filed for the county each year (2026 to June 30, 2026). Before 1996 NOAA recorded only tornadoes (from 1950), thunderstorm wind and hail (from 1955).
- recorded, no damage figure
- under $100,000
- $100,000 or more
- $1 million or more
- $10 million or more, or a death
- $100 million or more, or 10 deaths
- a year's colour: its recorded damage or deaths
- a year with a death
- 1955: wind and hail recorded from 1955
- 1996: all 48 event types from 1996
- Storm records
- 1,610on 988 days, 1950 to June 30, 2026
- Deaths recorded
- 120 injuries
- Damage, 2025 dollars
- $14Mas filed (scale steps before 1993)
- Tornadoes
- 4strongest F0
- FEMA declarations
- 16latest 2024
Source: NOAA NCEI Storm Events Database, records through June 30, 2026 (file revision 20260918); damage converted to 2025 dollars with the BLS CPI-U. Search the record at NCEI. BLS consumer price index.
What hazards hit Lewis and Clark County most?
The most frequent records are high wind and dust records: 746 since 1996. The rank column places the county among Montana's counties by days with a record per 1,000 square miles of land over each hazard's complete period.
| Hazard | Records | Days | First, last | Killed | Injured | Damage | Rank in state |
|---|---|---|---|---|---|---|---|
| High wind and dust storms | 746 | 466 | 1996-2026 | 0 | 1 | $573K | 6 of 56 |
| Winter storms | 463 | 313 | 1996-2026 | 1 | 5 | $3.7M | 19 of 56 |
| Hail | 118 | 78 | 1955-2026 | 0 | 0 | $4K | 39 of 56 |
| Severe thunderstorm wind | 114 | 83 | 1974-2025 | 0 | 0 | $34K | 29 of 56 |
| Extreme cold | 46 | 26 | 2002-2025 | 0 | 0 | – | 30 of 56 |
| Floods | 41 | 33 | 1999-2024 | 0 | 0 | $1.3M | 19 of 56 |
| Wildfires | 32 | 31 | 2000-2026 | 0 | 4 | $8.6M | 1 of 56 |
| Heavy rain | 29 | 9 | 2019-2022 | 0 | 0 | – | 22 of 56 |
| Fog, smoke and funnel clouds | 10 | 7 | 1996-2022 | 0 | 0 | – | 25 of 56 |
| Landslides and avalanches | 4 | 4 | 2012-2025 | 0 | 0 | $22K | 18 of 56 |
| Tornadoes | 4 | 4 | 1953-1997 | 0 | 0 | $4K | 39 of 56 |
| Lightning | 3 | 3 | 2003-2023 | 0 | 10 | – | 12 of 56 |
Source: NOAA NCEI Storm Events Database (county and forecast-zone records attributed to the county; a zone record shows its own totals on each county it covers). Days: dates with at least one record of the hazard in the county. Ranks: days with a record per 1,000 square miles of land (Census Bureau 2024 Gazetteer), since 1950 for tornadoes, 1955 for hail and thunderstorm wind, 1996 for the rest.
How many tornadoes has Lewis and Clark County had?
NOAA records 4 tornadoes in Lewis and Clark County from 1953 to 1997, the strongest rated F0, with 0 deaths and 0 injuries recorded in the county. A tornado that crossed a county line is counted in each county it touched, with the length of its path inside the county.
Counted as whole tornadoes rather than county records, the Storm Prediction Center's database holds 6 tornadoes whose track touched Lewis and Clark County since 1950 (NOAA's county records number 4: they file a crossing tornado once per county segment, and the two databases differ on some tracks); along their whole tracks they killed 0 people.
Map of the strongest tornado tracks in Montana.
Every tornado record filed for Lewis and Clark County (4)
| Date | Place | Character | Killed | Injured | Damage |
|---|---|---|---|---|---|
| 1997-06-27 | Helena, Lewis and Clark County | F0 0.1 mi x 10 yd | 0 | 0 | $4K |
| 1992-07-09 | Lewis and Clark County | F0 0.1 mi x 10 yd | 0 | 0 | – |
| 1960-07-22 | Lewis and Clark County | F0 1 mi x 10 yd | 0 | 0 | – |
| 1953-06-07 | Lewis and Clark County | 0 | 0 | – |
Source: NOAA NCEI Storm Events Database, tornado records by county (path length in the county, maximum width); ratings as published: F scale before February 1, 2007, EF scale after. Whole-track figures: NOAA Storm Prediction Center tornado database (1950-2025). SPC severe weather database.
When was the last damaging storm in Lewis and Clark County?
The most recent record with damage, injuries or deaths is the September 14, 2025 thunderstorm wind ($1,000 in damage in 2025 dollars).
| Date | Record | Character | Killed | Injured | Damage |
|---|---|---|---|---|---|
| 2026-06-25 | HailEast Helena, Lewis and Clark County | 1.00 in hail | 0 | 0 | – |
| 2026-06-25 | HailHelena Regional Arp, Lewis and Clark County | 1.00 in hail | 0 | 0 | – |
| 2026-06-25 | HailIron, Lewis and Clark County | 1.00 in hail | 0 | 0 | – |
| 2026-06-16 | High WindLewis and Clark County · forecast zone Upper Blackfoot And Macdonald Pass | 61 kt wind | 0 | 0 | – |
| 2026-05-14 | High WindLewis and Clark County and Teton County · forecast zone Southern High Plains | 73 kt wind | 0 | 0 | – |
| 2026-05-13 | High WindLewis and Clark County and Broadwater County · forecast zone Canyon Ferry Area | 50 kt wind | 0 | 0 | – |
| 2026-05-13 | High WindLewis and Clark County and Cascade County · forecast zone Gates Of The Mountains | 54 kt wind | 0 | 0 | – |
| 2026-05-13 | High WindLewis and Clark County · forecast zone Upper Blackfoot And Macdonald Pass | 77 kt wind | 0 | 0 | – |
| 2026-04-07 | High WindLewis and Clark County and Teton County · forecast zone Southern High Plains | 68 kt wind | 0 | 0 | – |
| 2026-04-07 | High WindLewis and Clark County · forecast zone Helena Valley | 53 kt wind | 0 | 0 | – |
| 2026-04-07 | High WindLewis and Clark County and 3 more · forecast zone Big Belt, Bridger And Castle Mountains | 56 kt wind | 0 | 0 | – |
| 2026-03-25 | High WindLewis and Clark County and 3 more · forecast zone Big Belt, Bridger And Castle Mountains | 54 kt wind | 0 | 0 | – |
Source: NOAA NCEI Storm Events Database; every record of 2025-2026 is listed, earlier ones when they caused deaths, injuries or $250,000 of damage (2025 dollars), and every tornado.
The deadliest and costliest records
| Date | Record | Character | Killed | Injured | Damage |
|---|---|---|---|---|---|
| 2019-04-28 | Winter WeatherLewis and Clark County · forecast zone Southern Lewis And Clark The Montana Standard Reported the following - Late Sunday morning April 28th, two fishing boats capsized on Upper Holter Lake in Southern Lewis and Clark County. The accident resulted in one fatality and sent five others to the hospital. Winter weather conditions may have played a role in the crash. Snow with gusty ... | 1 | 5 | – | |
| 2003-08-13 | LightningCraig, Lewis and Clark County A youth group of kids and a few adults were rafting down the Missouri River during the late afternoon hours on the 13th. A fast moving thunderstorm approached and a lightning bolt struck the raft. Most of the people in the raft fell into the water. Four children suffered minor burns. One adult was struck directly by ... | 0 | 5 | – | |
| 2022-06-18 | LightningGilman, Lewis and Clark County A 34 year old female struck by lightning, which also injured a 40 year old male and another male of unknown age. Individuals were driving a vehicle that had a kayak strapped to top of vehicle. Strap came loose and the group pulled over and got out to tighten the strap when they were struck. Female was flung six feet, ... | 0 | 3 | – | |
| 2023-06-11 | LightningHelena Regional Arp, Lewis and Clark County Two male individuals (ages 22 and 21) were struck by lightning while playing disc golf. Both were knocked unconscious. One of the individuals regained consciousness and performed CPR on the other, who was later flown to Salt Lake City for advanced medical care. As of early July 2023, both individuals were recovering ... | 0 | 2 | – | |
| 2000-08-01 | WildfireHelena, Lewis and Clark County Continued Canyon Ferry Complex - includes Broadwater County, 38570 acres burned, cause unknown, 13 residents destroyed, 37 outbuildings destroyed. | 0 | 2 | $4.3M | |
| 2000-07-23 | WildfireHelena, Lewis and Clark County Canyon Ferry Complex - includes Broadwater County, 38570 acres burned, 13 residences destroyed, 37 outbuildings destroyed, unknown cause, continued past July 31. | 0 | 2 | $4.3M | |
| 2000-01-09 | High WindLewis and Clark County · forecast zone Broadwater / Jefferson / Meagher / Central And Southern Lewis And Clark Lincoln...double-wide trailer overturned 2 mi W of Whitehall. | 70 kt wind | 0 | 1 | $86K |
| Date | Record | Character | Killed | Injured | Damage |
|---|---|---|---|---|---|
| 2000-07-23 | WildfireHelena, Lewis and Clark County | 0 | 2 | $4.3M | |
| 2000-08-01 | WildfireHelena, Lewis and Clark County | 0 | 2 | $4.3M | |
| 2022-12-07 | BlizzardLewis and Clark County and Teton County · forecast zone Southern Rocky Mountain Front | 0 | 0 | $1.0M | |
| 2022-07-03 | Flash FloodHelena, Lewis and Clark County | 0 | 0 | $706K | |
| 2003-03-12 | FloodLewis and Clark County · forecast zone Southern Lewis And Clark | 0 | 0 | $401K | |
| 2000-01-09 | High WindLewis and Clark County · forecast zone Broadwater / Jefferson / Meagher / Central And Southern Lewis And Clark | 70 kt wind | 0 | 1 | $86K |
| 2000-07-13 | Thunderstorm WindHelena, Lewis and Clark County | 70 kt wind | 0 | 0 | $17K |
| 2025-07-31 | Debris FlowCanyon Ferry, Lewis and Clark County | 0 | 0 | $11K |
Source: NOAA NCEI Storm Events Database: deaths and injuries direct and indirect; damage is property plus crops as estimated by the National Weather Service, converted to 2025 dollars.
Is it getting more frequent?
Records per decade for Lewis and Clark County's most frequent hazards. Counts rose everywhere after 1996, when NOAA began recording every event type, so compare decades within a hazard's complete period only (the shaded cells come before it).
| Hazard | 1950s | 1960s | 1970s | 1980s | 1990s | 2000s | 2010s | 2020-26 |
|---|---|---|---|---|---|---|---|---|
| High wind and dust storms | – | – | – | – | 11 | 118 | 312 | 305 |
| Winter storms | – | – | – | – | 33 | 140 | 131 | 159 |
| Hail | 3 | 3 | 4 | 9 | 17 | 47 | 24 | 11 |
| Severe thunderstorm wind | 0 | 0 | 5 | 14 | 9 | 36 | 17 | 33 |
| Extreme cold | – | – | – | – | 0 | 2 | 8 | 36 z |
| Floods | – | – | – | – | 1 | 14 | 18 | 8 |
Extreme cold in the 2020-26: 36 records against 8 in the decade before, 36 of them forecast-zone records. Cells marked z rose mostly through zone records. The local National Weather Service office files these once per forecast zone, so a change in how it draws its zones or splits a storm into records moves this count as much as the weather does; read it beside the Lewis and Clark County days with a record above.
Source: NOAA NCEI Storm Events Database, records per calendar decade; zone records from the CZ_TYPE field (Z).
What time of year?
Records by month in Lewis and Clark County. The two busiest months are in violet.
The values, month by month
Jan 197 · Feb 181 · Mar 155 · Apr 112 · May 91 · Jun 131 · Jul 114 · Aug 75 · Sep 52 · Oct 122 · Nov 180 · Dec 200 (records).
Source: NOAA NCEI Storm Events Database, records by the month they began.
Federal disaster declarations for Lewis and Clark County
FEMA's register lists 16 declarations that include Lewis and Clark County: 7 major disasters, 2 emergencies and 7 fire management assistance declarations. Most were for fire (8) and flood (3).
| Declared | Number | Type | Title |
|---|---|---|---|
| 2024-07-12 | FM-5507 | Fire | Horse Gulch Fire |
| 2020-03-31 | DR-4508 | Biological | Covid-19 Pandemic |
| 2020-03-13 | EM-3476 | Biological | Covid-19 |
| 2019-07-28 | FM-5286 | Fire | North Hills Fire |
| 2018-10-31 | DR-4405 | Flood | Flooding |
| 2017-09-09 | FM-5208 | Fire | Alice Creek Fire |
| 2012-06-26 | FM-2987 | Fire | Corral Fire |
| 2011-06-17 | DR-1996 | Severe Storm | Severe Storms and Flooding |
| 2007-09-16 | FM-2730 | Fire | Country Club Fire |
| 2005-09-13 | EM-3253 | Hurricane | Hurricane Katrina Evacuation |
| 2003-08-20 | FM-2492 | Fire | Mt-Lincoln Fire Complex - 08/14/2003 |
| 2000-08-30 | DR-1340 | Fire | Wildfires |
| 2000-07-24 | FM-2314 | Fire | Mt - Central Zone 3b Fire Complex |
| 1996-02-23 | DR-1105 | Severe Storm | Severe Storms, Flooding, and Ice Jams |
| 1981-05-27 | DR-640 | Flood | Severe Storms & Flooding |
| 1975-06-28 | DR-472 | Flood | Rains, Showmelt, Storms & Flooding |
Source: FEMA OpenFEMA Disaster Declarations Summaries (v2), declarations through October 2, 2026; one declaration is counted once however many areas it names. OpenFEMA dataset page.
How many floods has Lewis and Clark County had?
NOAA's Storm Events Database holds 41 flood or flash flood records for Lewis and Clark County from 1999 to 2024, on 33 days, with 0 deaths. By flood insurance claims since 1978 (OpenFEMA, as of September 8, 2026), Lewis and Clark County ranks 1293rd of 2,942 U.S. counties.
The National Flood Insurance Program has paid $432,000 on 102 claims filed in Lewis and Clark County; the most in one year was 38 in 2018. Claims count insured losses only: uninsured flood damage is not in this file.
The values, year by year
1978: 3 · 1979: 3 · 1980: 2 · 1981: 14 · 1982: 1 · 1983: 2 · 1986: 6 · 1996: 7 · 1997: 1 · 1998: 1 · 2009: 1 · 2010: 1 · 2011: 17 · 2014: 3 · 2018: 38 · 2019: 1 · 2024: 1; the other years: 0.
Source: FEMA OpenFEMA NFIP Redacted Claims, as of September 8, 2026; claims by year of loss, payments in the dollars of the year paid. OpenFEMA dataset page.
FEMA's modeled risk for Lewis and Clark County
FEMA's National Risk Index rates Lewis and Clark County Relatively Low overall, with an expected annual loss of $34.8 million. These are FEMA's model estimates of future loss from 18 hazards, not a count of what happened; they can differ from the record above.
| Hazard | Risk rating | Expected annual loss | Modeled frequency |
|---|---|---|---|
| Winter Weather | Very High | $1.6M | 44 a year (modeled) |
| Cold Wave | Relatively High | $13M | 6.3 a year (modeled) |
| Landslide | Relatively Moderate | $154K | 2.2 a year (modeled) |
| Wildfire | Relatively Moderate | $2.5M | once in about 423 years (modeled) |
| Avalanche | Relatively Moderate | $457K | once in about 30 years (modeled) |
| Lightning | Relatively Moderate | $504K | 25 a year (modeled) |
| Earthquake | Relatively Low | $3.8M | once in about 137 years (modeled) |
| Riverine Flooding | Relatively Low | $12M | 1.1 a year (modeled) |
Source: FEMA National Risk Index, county table, December 2025 release. FEMA's National Risk Index map.
Counties that share a border with Lewis and Clark County
Source: U.S. Census Bureau county adjacency file; NOAA NCEI Storm Events Database, records since 1950. The Census Bureau's adjacency file.
Next
- Tornadoes in MontanaEvery Montana tornado since 1950 and the counties with the most per square mile
- High wind and dust storms in MontanaThe state's high wind and dust records, by county, year and month
- The Montana recordEvery hazard in the state, its deadliest events and its federal declarations
- FEMA's risk rating for each hazard in Lewis and Clark CountyThe hazard risk calculator: 18 hazards beside the county's record
- Download Lewis and Clark County's FEMA declarations (CSV)16 rows: every declaration that named the county, for your own analysis