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Weather & Climate in Garrison, MT
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Garrison has a cool climate with an average annual temperature of 41°F (5°C). Winters average 22°F in January while summers reach 63°F in July. The area gets 273 sunny days per year, well above the U.S. average of 205 / making it one of the sunnier locations in the country. Annual precipitation totals 18.8 inches (drier than the 38-inch national average). Air quality is rated Good with a median AQI of 26 / among the cleanest air in the country. The city sits at an elevation of 4,395 feet.
Temperature
22°F Jan (-6°C)
63°F Jul (17°C)
| Annual Average | 41.0°F |
| 24% below US avg | |
| January Average | 22°F (-6°C) |
| July Average | 63°F (17°C) |
| Sunny Days | 273 days/yr |
Geography
| Elevation | 4,395 ft (1,340 m) |
| Area | 9.6 sq mi (25.0 km²) |
| Population Density | 14/sq mi |
| Coordinates | 46.5402°N, 112.8168°W |
| Timezone | America/Denver |
| County | Powell County County |
| Nearest Airport | Helena Regional (HLN) 40 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 26.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 10.0 / 100 |
| Social Vulnerability | 58.1 / 100 |
| Community Resilience | 19.4 / 100 |
Hazard Breakdown
| Tornado | Very Low |
| Earthquake | Very Low |
| Wildfire | Relatively Low |
| Flood | Very Low |
| Hail | Very Low |
| Strong Wind | Very Low |
| Heat Wave | Very Low |
| Winter Weather | Relatively Moderate |
| Lightning | Very Low |
| Ice Storm | Very Low |
| Drought | Very Low |
| Cold Wave | Relatively Low |
| Landslide | Relatively Moderate |
| Avalanche | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
520 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M5.8.
| Jul 6, 2017 | 11 km SE of Lincoln, Montana | M5.8 | 42 km | 12 km |
| Jul 26, 2005 | 16 km N of Dillon, Montana | M5.6 | 132 km | 13 km |
| Jul 6, 2017 | 15 km S of Lincoln, Montana | M5.0 | 32 km | 15 km |
| May 8, 2007 | 8 km NNW of Alder, Montana | M4.4 | 138 km | 14 km |
| Jul 6, 2017 | 14 km SE of Lincoln, Montana | M4.4 | 41 km | 10 km |
| Jan 30, 2016 | 19 km E of Lincoln, Montana | M4.3 | 54 km | 2 km |
| Oct 28, 1998 | 18 km S of Whitehall, Montana | M4.3 | 107 km | 5 km |
| Aug 16, 2019 | 4 km NW of Manhattan, Montana | M4.2 | 133 km | 2 km |
| Apr 8, 2000 | 8 km ENE of Townsend, Montana | M4.1 | 110 km | 5 km |
| Aug 6, 2019 | 3 km NW of Manhattan, Montana | M4.1 | 134 km | 5 km |
| Jun 18, 2006 | 6 km S of Pony, Montana | M4.1 | 126 km | 12 km |
| Oct 7, 2024 | 11 km E of Dillon, Montana | M4.1 | 148 km | 17 km |
| Sep 3, 2016 | 16 km S of Whitehall, Montana | M4.0 | 105 km | 8 km |
| Jul 6, 2017 | 14 km SSE of Lincoln, Montana | M4.0 | 37 km | 9 km |
| Jul 19, 2002 | 43 km NE of Seeley Lake, Montana | M4.0 | 101 km | 25 km |
| Mar 6, 2009 | 18 km S of Whitehall, Montana | M4.0 | 107 km | 12 km |
| Jul 27, 2005 | 18 km N of Dillon, Montana | M4.0 | 130 km | 5 km |
| Jan 18, 2006 | 18 km NNE of Dillon, Montana | M4.0 | 133 km | 9 km |
| Jun 28, 2000 | 21 km SE of Clinton, Montana | M4.0 | 56 km | 10 km |
| Jul 17, 2017 | 12 km ESE of Lincoln, Montana | M4.0 | 44 km | 13 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
14 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF1.
| Date | Rating | Distance | Path | Fatalities |
| Jun 28, 1982 | EF1 | 19 km | 0.5 mi | 0 |
| Sep 15, 1997 | EF0 | 49 km | 0.1 mi | 0 |
| Jun 27, 1997 | EF0 | 60 km | 0.1 mi | 0 |
| Jun 21, 1993 | EF0 | 73 km | 0.1 mi | 0 |
| Jun 11, 1993 | EF0 | 64 km | 0.1 mi | 0 |
| Jul 9, 1992 | EF0 | 46 km | 0.1 mi | 0 |
| Jun 12, 1992 | EF0 | 99 km | 0.1 mi | 0 |
| May 16, 1991 | EF0 | 94 km | 0.2 mi | 0 |
| Aug 15, 1990 | EF0 | 98 km | 0.1 mi | 0 |
| Aug 11, 1988 | EF0 | 32 km | 2.0 mi | 0 |
| May 4, 1971 | EF0 | 17 km | 0.5 mi | 0 |
| May 17, 1962 | EF0 | 16 km | 0.1 mi | 0 |
| Jul 22, 1960 | EF0 | 63 km | 1.0 mi | 0 |
| Jun 7, 1953 | EF0 | 96 km | 0.1 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
20 wildfires (100+ acres) recorded within 100 km. Largest: RICE RIDGE (171,473 acres, 2017).
| Year | Name | Acres Burned | Distance |
| 2017 | RICE RIDGE | 171,473 | 86 km |
| 1988 | CANYON CREEK | 167,875 | 78 km |
| 2017 | MEYERS | 68,711 | 83 km |
| 2007 | SAWMILL COMPLEX (WYMAN 2) | 68,236 | 66 km |
| 2000 | MUSSIGBROD COMPLEX (MUSSIGBROD) | 64,810 | 94 km |
| 2021 | ALDER CREEK | 38,189 | 86 km |
| 2003 | LINCOLN COMPLEX (SNOWBANK) | 36,987 | 63 km |
| 1988 | CANYON CREEK | 35,865 | 79 km |
| 2007 | JOCKO LAKES | 35,759 | 97 km |
| 2017 | LITTLE HOGBACK | 34,646 | 61 km |
| 2017 | ALICE CREEK | 29,971 | 73 km |
| 2012 | ELBOW PASS COMPLEX | 28,989 | 94 km |
| 2017 | LIBERTY | 27,731 | 93 km |
| 1984 | NORTH HILL | 27,162 | 76 km |
| 2000 | CANYON FERRY COMPLEX (CAVE GULCH) | 26,997 | 93 km |
| 2021 | HAYSTACK | 26,118 | 62 km |
| 2003 | COONEY RIDGE | 25,741 | 79 km |
| 2007 | CONGER CREEK | 22,936 | 76 km |
| 2000 | MONTURE-SPREAD RIDGE (MONTURE) | 22,493 | 89 km |
| 2003 | MINERAL-PRIMM (MINERAL AND PRIMM) | 20,888 | 91 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 22°F (-6°C) | 0.9 in | |
| February | 25°F (-4°C) | 0.6 in | Driest |
| March | 32°F (-0°C) | 0.8 in | |
| April | 39°F (4°C) | 1.1 in | |
| May | 48°F (9°C) | 2.0 in | Wettest |
| June | 56°F (13°C) | 1.9 in | |
| July | 63°F (17°C) | 1.2 in | Warmest |
| August | 62°F (17°C) | 1.3 in | |
| September | 53°F (12°C) | 1.2 in | |
| October | 43°F (6°C) | 0.8 in | |
| November | 30°F (-1°C) | 0.8 in | |
| December | 22°F (-6°C) | 0.9 in | Coldest |
Garrison has a seasonal temperature swing of 41°F / from 22°F in December to 63°F in July. Total annual precipitation is 13.5 inches, with May being the wettest month (2.0") and February the driest (0.6").