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Weather & Climate in St. Mary, MT
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
St. Mary has a cool climate with an average annual temperature of 40°F (4°C). Winters average 23°F in January while summers reach 60°F in July. The area gets 269 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 26.1 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 4,634 feet.
Temperature
23°F Jan (-5°C)
60°F Jul (15°C)
| Annual Average | 39.5°F |
| 27% below US avg | |
| January Average | 23°F (-5°C) |
| July Average | 60°F (15°C) |
| Sunny Days | 269 days/yr |
Geography
| Elevation | 4,634 ft (1,412 m) |
| Area | 0.8 sq mi (1.9 km²) |
| Population Density | 279/sq mi |
| Coordinates | 48.7429°N, 113.4275°W |
| Timezone | America/Denver |
| County | Glacier County County |
| Nearest Airport | Glacier Park International (FCA) 48 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 26.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 51.5 / 100 |
| Social Vulnerability | 99.2 / 100 |
| Community Resilience | 28.2 / 100 |
Hazard Breakdown
| Tornado | Very Low |
| Earthquake | Relatively Low |
| Wildfire | Relatively Low |
| Flood | Relatively Low |
| Hail | Very Low |
| Strong Wind | Very Low |
| Heat Wave | Very Low |
| Winter Weather | Relatively High |
| Lightning | Relatively Low |
| Ice Storm | Very Low |
| Drought | Relatively Low |
| Cold Wave | Relatively High |
| Landslide | Relatively Low |
| Avalanche | Relatively Moderate |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
142 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M4.6.
| Mar 4, 2000 | 35 km S of Pincher Creek, Canada | M4.6 | 65 km | 1 km |
| Mar 22, 2006 | 8 km SSW of Rexford, Montana | M4.3 | 130 km | 8 km |
| Jun 29, 1995 | 2 km NNW of Kila, Montana | M4.1 | 102 km | 5 km |
| May 2, 1995 | 2 km NW of Kila, Montana | M4.1 | 102 km | 9 km |
| Apr 15, 1998 | 11 km NE of Swan Lake, Montana | M4.1 | 85 km | 4 km |
| Jul 19, 2002 | 43 km NE of Seeley Lake, Montana | M4.0 | 149 km | 25 km |
| Apr 1, 1992 | 10 km ESE of Swan Lake, Montana | M4.0 | 98 km | 5 km |
| Jan 20, 1998 | 15 km SSE of Happys Inn, Montana | M4.0 | 149 km | 7 km |
| May 2, 1995 | 3 km WNW of Kila, Montana | M3.8 | 104 km | 9 km |
| Jul 2, 1992 | 4 km SSE of South Browning, Montana | M3.8 | 41 km | 10 km |
| Sep 26, 2004 | 14 km WSW of Pablo, Montana | M3.8 | 146 km | 17 km |
| May 1, 1997 | 35 km SSE of Magrath, Canada | M3.8 | 71 km | 5 km |
| Oct 2, 1995 | 18 km E of Finley Point, Montana | M3.7 | 117 km | 5 km |
| Aug 19, 1999 | 12 km ENE of Happys Inn, Montana | M3.7 | 134 km | 14 km |
| Jan 13, 2010 | 36 km NE of Seeley Lake, Montana | M3.7 | 147 km | 21 km |
| May 10, 1990 | 47 km SSW of Heart Butte, Montana | M3.6 | 100 km | 5 km |
| Sep 29, 2009 | 42 km NW of Santa Rita, Montana | M3.6 | 65 km | 21 km |
| Jun 5, 1991 | 18 km SW of Shelby, Montana | M3.6 | 112 km | 5 km |
| Feb 2, 1997 | 1 km NNE of Lindisfarne, Montana | M3.6 | 118 km | 5 km |
| Oct 26, 1999 | 23 km WNW of Niarada, Montana | M3.6 | 143 km | 12 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
6 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF1.
| Date | Rating | Distance | Path | Fatalities |
| Jun 13, 2006 | EF1 | 58 km | 10.0 mi | 0 |
| Jun 6, 1994 | EF1 | 92 km | 0.1 mi | 0 |
| Jun 1, 1977 | EF1 | 91 km | 0.1 mi | 0 |
| Nov 4, 2013 | EF0 | 98 km | 0.8 mi | 0 |
| Apr 9, 2008 | EF0 | 89 km | 0.0 mi | 0 |
| Sep 10, 2000 | EF0 | 76 km | 2.0 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
20 wildfires (100+ acres) recorded within 100 km. Largest: MOOSE (73,210 acres, 2001).
| Year | Name | Acres Burned | Distance |
| 2001 | MOOSE | 73,210 | 51 km |
| 2003 | ROBERT | 54,500 | 50 km |
| 2007 | FOOL CREEK | 53,912 | 93 km |
| 2003 | WEDGE CANYON | 51,987 | 72 km |
| 2015 | FAMILY PEAK COMPLEX | 49,769 | 66 km |
| 2007 | SKYLAND | 41,237 | 50 km |
| 1988 | RED BENCH | 33,845 | 61 km |
| 2006 | RED EAGLE | 32,563 | 7 km |
| 2003 | RAMPAGE COMPLEX (DOUBLE MOUNTAIN 2) | 23,680 | 41 km |
| 2015 | TRAIL CREEK | 22,338 | 86 km |
| 2017 | SCALP | 20,309 | 92 km |
| 2003 | BLACKFOOT LAKE COMPLEX (BLACKFOOT LAKE) | 18,274 | 68 km |
| 2015 | THOMPSON | 18,049 | 26 km |
| 2003 | TRAPPER CREEK FIRE (TRAPPER CREEK) | 18,028 | 31 km |
| 2017 | STRAWBERRY | 17,781 | 79 km |
| 2017 | SPRAGUE | 16,897 | 35 km |
| 2018 | HOWE RIDGE | 14,747 | 39 km |
| 2021 | GREENHOUSE | 14,501 | 45 km |
| 2007 | CORPORAL | 14,054 | 95 km |
| 2003 | TRAPPER CREEK FIRE (WOLF GUN) | 13,920 | 43 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 23°F (-5°C) | 1.5 in | |
| February | 23°F (-5°C) | 1.3 in | Driest |
| March | 27°F (-3°C) | 1.5 in | |
| April | 35°F (2°C) | 1.9 in | |
| May | 44°F (7°C) | 2.9 in | |
| June | 52°F (11°C) | 3.3 in | Wettest |
| July | 60°F (15°C) | 1.7 in | Warmest |
| August | 58°F (14°C) | 1.9 in | |
| September | 49°F (10°C) | 2.0 in | |
| October | 40°F (5°C) | 1.3 in | |
| November | 28°F (-2°C) | 1.5 in | |
| December | 21°F (-6°C) | 1.4 in | Coldest |
St. Mary has a seasonal temperature swing of 39°F / from 21°F in December to 60°F in July. Total annual precipitation is 22.2 inches, with June being the wettest month (3.3") and February the driest (1.3").