Helena

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond this area.
2. Weak tornadoes were under-recorded before Doppler radar coverage became national in the early 1990s, so earlier decades read low. Ratings use the Fujita scale before February 2007 and the Enhanced Fujita scale after.

Storm Prediction Center severe weather database, 1950 to 2025.

Every large fire

1. Large fires mapped by the Monitoring Trends in Burn Severity program since 1984: 1,000 acres or more in the West, 500 or more in the East. Prescribed burns are excluded. Acres here are the part of each perimeter inside this place.

Monitoring Trends in Burn Severity (USGS and U.S. Forest Service), 1984 to 2026.

Smoke overhead

1. A smoke day is a date on which a smoke plume traced by NOAA Hazard Mapping System analysts from satellite imagery covered this place's point (the county's population centre or the city centre). Counts here are of medium or heavy smoke. Since 2018 analysts have often drawn light smoke as one area over most of the continent, so light-smoke counts are not comparable from year to year. The plumes show smoke anywhere in the air above, not air quality at the ground, and smoke hidden by cloud is missed.

NOAA Hazard Mapping System smoke analysis, 2011 to 2026, retrieved October 30, 2026.

Flood insurance figures are for Lewis and Clark County, the county that contains Helena.

Claims by ZIP code

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).

OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026. NOAA Storm Events through 2026.

River crests

River gauges in Lewis and Clark County, the county that contains Helena.

River gauges

1. Crests are the highest and the recent crests the National Weather Service lists for each river gauge in the county that has a flood stage, not every flood. Flood categories use each gauge's current flood stages; crests from before levees, dams or channel changes may not be comparable. Crests measured on an old datum are left out of the rankings.

NOAA National Water Prediction Service gauge records, retrieved October 30, 2026.

The drought index is for Lewis and Clark County, the county that contains Helena.

1. The Palmer Drought Severity Index is computed by NOAA each month from the county's average temperature and precipitation, relative to the county's own climate. Zero is normal; -3 or lower is severe drought and -4 or lower extreme drought. It describes the long-term balance of moisture, not water supply or crop losses.

NOAA NCEI nClimDiv county Palmer Drought Severity Index, 1895 to September 2026, issued October 6, 2026.

Every earthquake of magnitude 4 or more within 50 miles

1. Earthquakes of magnitude 2.5 or more in the USGS Comprehensive Catalog since 1900. Within 50 miles means the epicentre lies within 50 miles of the city centre.
2. Small earthquakes were under-recorded before the modern seismic networks of the 1970s and are still missed in remote areas, so early decades read low. Magnitudes are as the catalogue reports them and mix scales (moment, local and body-wave).

USGS ANSS Comprehensive Earthquake Catalog, 1900 to present, retrieved October 30, 2026.

Mapped landslides

Landslides mapped in Lewis and Clark County.

Mapped by NASA (4).

1. Landslides mapped in the USGS compilation of landslide inventories across the United States (version 3.0, 2025), rated probable or better. The compilation joins inventories made by federal and state agencies for different purposes and areas, so the number mapped in a county reflects how closely it has been surveyed as much as how often its slopes fail. An area with few records may simply not have been mapped. Deaths are as recorded in the inventories; a slide listed in two inventories is counted once.

USGS Landslide Inventories across the United States, version 3.0, retrieved October 27, 2026.

More event types since 1996

Costliest events since 1996

1. Jul 23, 2000Wildfire$2.5 million
   National Weather Service narrative

   Canyon Ferry Complex - includes Broadwater County, 38570 acres burned, 13 residences destroyed, 37 outbuildings destroyed, unknown cause, continued past July 31.

2. Aug 1, 2000Wildfire$2.5 million
   National Weather Service narrative

   Continued Canyon Ferry Complex - includes Broadwater County, 38570 acres burned, cause unknown, 13 residents destroyed, 37 outbuildings destroyed.

3. Jun 8, 2002Winter Storm, Southern Rocky Mountain Front$1.6 million
   National Weather Service narrative

   A major late season winter storm affected much of the Rocky Mountain Front from June 8th to June 10th. The snow began to fall at higher elevations on Friday evening, with rain at the lower elevations. Buy Saturday morning, heavy snow was falling across the entire Rocky Mountain Front. The snow was heavy at times throughout Saturday. On Saturday night, blizzard conditions were experienced over the Northern Rocky Mountain Front. The snow began to diminish in intensity on Monday evening. By then, snow accumulations ranged from 3 to 4 feet over the Plains, to 5 to 7 feet above 5000 feet.This snow had a very high moisture content, which caused 301 power poles to break, 232 power pole…

4. Dec 7, 2022Blizzard, Southern Rocky Mountain Front$1.0 million
   National Weather Service narrative

   Trained spotter approximately 17 miles west-southwest of Bynum (close to the border of MT zones 307 and 308) reported blizzard conditions for 7 hours. A local volunteer fire department submitted photos from Stonewall Mountain of a communications tower being downed due to the weight of significant riming from snow/ice/wind. The downed tower had been there for 30 years and was the communications tower for multiple emergency response agencies.

5. Jul 3, 2022Flash Flood$700,000
   National Weather Service narrative

   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.

6. Mar 12, 2003Flood, Southern Lewis And Clark$250,000
   National Weather Service narrative

   With a major snowstorm falling in the mountains in the Helena Valley on March 6th through the 10th, and temperatures quickly rising to near 70 degrees by the 12th, a rapid snow melt occurred in the mountains. This snow melt quickly filled all small streams and creeks. As the snow continued to melt during the afternoon hours, the creeks began to overflow, as some culverts were blocked with ice and debris. The result was some nearby homes and roads next to the creeks were either damaged or washed out. Water was up to a foot deep in some locations. Damage reports in the Helena Valley included about 20 homes with flood damage, and a few secondary roads washed out. The damage cost was…

7. Apr 9, 2023Flood$100,000
   National Weather Service narrative

   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.

8. Jan 4, 2001High Wind, Southern Rocky Mountain Front$70,000
   National Weather Service narrative

   Choteau 10 NW...damaging winds at Blackleaf...damage as a result of an overturned tractor trailer (trailer unit only) near Bynum...damage to large crop sprinkler units just north of Choteau...damage to windows and trampoline at residence in Choteau.

9. Jul 20, 2012Flash Flood$50,000
   National Weather Service narrative

   Railroad tracks washed out near Scratch Gravel Hills.

10. Mar 6, 2003Winter Storm, Southern Rocky Mountain Front$15,000
    National Weather Service narrative

    Heavy snow fell over the entire Rocky Mountain Front from March 6th to March 10th. Snowfall amounts generally ranged from 6 to 10 inches per day. However, in a 24 hour period starting at 0400 MST on the 7th, some areas did receive over 2 feet of snow. By the end of the storm, many locations above 5000 feet had received between 3 and 5 feet of snow.The amount of the snowfall over this 5 day period caused a car port to collapse, crushing a vehicle underneath it.Here is a list of some of the snowfalls reported for the total storm:56 inches at East Glacier; 48 inches at Landers Park; 37 inches at Lincoln 6N (SNOTEL); 36 inches at Lincoln; 32 inches at Many Glacier; 26 inches at Pike…

1. Storm Events records before 1996 cover only tornadoes, thunderstorm wind and hail. Damage figures are as reported by the National Weather Service at the time, not adjusted for inflation.

NOAA NCEI Storm Events Database, 1950 to 2026, issued October 26, 2026.

All-time high

105°F2 times, most recently Jul 12, 2002

All-time low

−42°F2 times, most recently Feb 2, 1996

Warmest night

72°FJul 28, 2021

Coldest day

−23°FFeb 2, 1989

Wettest day

2.06 inMay 3, 1964

Snowiest day

18.8 inNov 11, 1959

Hottest year

2007mean 48.5°F

Coldest year

1951mean 39.9°F

Wettest year

197520.94 in

Driest year

19736.26 in

Snowiest season

86.5 in1988-89

Station Helena Airport Asos (USW00024144), 3,865 ft elevation, 1.5 miles from the city centre. Daily records from 1938 to October 27, 2026; 99.9% of days in the last 30 years are complete. Records at a single station can differ from a city’s official threaded record, which may combine several stations.

NOAA NCEI Global Historical Climatology Network Daily.

Declarations for Lewis and Clark County.

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).

OpenFEMA Disaster Declarations Summaries, retrieved October 30, 2026. Statewide declarations are not listed.

• Tornadoes NOAA Storm Prediction Center severe weather database, through 2025.
• Tropical cyclones NOAA National Hurricane Center HURDAT2 (Atlantic; Northeast and Central Pacific), through 2025.
• Wildfire USGS/USFS Monitoring Trends in Burn Severity, through 2026.
• Storm events NOAA NCEI Storm Events Database, through 2026.
• Flood insurance OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026.
• Declarations OpenFEMA Disaster Declarations Summaries v2, retrieved October 30, 2026.
• Weather records NOAA NCEI Global Historical Climatology Network Daily, station USW00024144.
• River crests NOAA National Weather Service, National Water Prediction Service river gauges, retrieved October 30, 2026.
• Drought NOAA NCEI nClimDiv county Palmer Drought Severity Index, through September 2026.
• Smoke NOAA NESDIS Hazard Mapping System smoke analysis, retrieved October 30, 2026.
• Landslides USGS Landslide Inventories across the United States, version 3.0 (2025).
• Earthquakes USGS ANSS Comprehensive Earthquake Catalog (ComCat), retrieved October 30, 2026.

Joins, thresholds and known limits are set out in the methodology. Found an error? Report it. Page built October 30, 2026.