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Weather & Climate in Westby, MT
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Westby has a cool climate with an average annual temperature of 39°F (4°C). Winters average 9°F in January while summers reach 67°F in July. The area gets 274 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 14.9 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 2,083 feet.
Temperature
9°F Jan (-13°C)
67°F Jul (20°C)
| Annual Average | 39.1°F |
| 28% below US avg | |
| January Average | 9°F (-13°C) |
| July Average | 67°F (20°C) |
| Sunny Days | 274 days/yr |
Geography
| Elevation | 2,083 ft (635 m) |
| Area | 0.5 sq mi (1.4 km²) |
| Population Density | 452/sq mi |
| Coordinates | 48.8705°N, 104.0571°W |
| Timezone | America/Denver |
| County | Sheridan County County |
| Nearest Airport | Williston Basin International (XWA) 44 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 26.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 15.1 / 100 |
| Social Vulnerability | 59.2 / 100 |
| Community Resilience | 12.0 / 100 |
Hazard Breakdown
| Tornado | Very Low |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Very Low |
| Hail | Very Low |
| Strong Wind | Relatively Low |
| Heat Wave | Very Low |
| Winter Weather | Relatively Moderate |
| Lightning | Very Low |
| Ice Storm | Relatively Low |
| Drought | Relatively Low |
| Cold Wave | Relatively Moderate |
| Landslide | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
5 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M3.8.
| Feb 25, 2014 | 23 km N of Brockton, Montana | M3.8 | 83 km | 5 km |
| Jul 29, 1998 | 16 km WNW of Froid, Montana | M3.8 | 73 km | 5 km |
| Nov 11, 1998 | 10 km SW of Grenora, North Dakota | M3.5 | 36 km | 5 km |
| Sep 28, 2012 | 22 km ESE of Williston, North Dakota | M3.3 | 105 km | 5 km |
| May 6, 2014 | 12 km NNW of Knife River, Montana | M2.6 | 150 km | 8 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
59 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF3. Total: 2 fatalities, 1 injury.
| Date | Rating | Distance | Path | Fatalities |
| Jul 26, 2010 | EF3 | 73 km | 18.0 mi | 2 |
| Jun 14, 1950 | EF3 | 22 km | 23.7 mi | 0 |
| Jun 27, 1982 | EF2 | 82 km | 0.4 mi | 0 |
| Jun 5, 1976 | EF2 | 96 km | 2.0 mi | 0 |
| Jul 2, 1971 | EF2 | 54 km | 10.0 mi | 0 |
| Sep 21, 1969 | EF2 | 75 km | 1.0 mi | 0 |
| Jun 13, 1953 | EF2 | 93 km | 0.1 mi | 0 |
| Jul 9, 2018 | EF1 | 36 km | 2.1 mi | 0 |
| Jun 11, 2007 | EF1 | 37 km | 3.0 mi | 0 |
| Jul 18, 2003 | EF1 | 56 km | 2.0 mi | 0 |
| Jul 21, 1999 | EF1 | 83 km | 1.0 mi | 0 |
| Jul 4, 1998 | EF1 | 98 km | 2.0 mi | 0 |
| Jun 29, 1991 | EF1 | 83 km | 0.2 mi | 0 |
| Jul 2, 1990 | EF1 | 33 km | 0.1 mi | 0 |
| Jul 13, 1980 | EF1 | 87 km | 0.1 mi | 0 |
| Jun 27, 1975 | EF1 | 73 km | 0.1 mi | 0 |
| Aug 5, 1969 | EF1 | 93 km | 0.1 mi | 0 |
| Aug 5, 1968 | EF1 | 80 km | 0.1 mi | 0 |
| Aug 18, 1962 | EF1 | 19 km | 0.1 mi | 0 |
| Jun 20, 1959 | EF1 | 93 km | 0.1 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
17 wildfires (100+ acres) recorded within 100 km. Largest: WILLIAMS CO WILDLAND FIRE (67,150 acres, 2024).
| Year | Name | Acres Burned | Distance |
| 2024 | WILLIAMS CO WILDLAND FIRE | 67,150 | 78 km |
| 1988 | BAINVILLE | 12,790 | 89 km |
| 2016 | FLAGSTAFF HILL | 9,129 | 66 km |
| 2017 | YOOPER | 7,834 | 100 km |
| 1999 | OUTLOOK | 6,292 | 54 km |
| 1999 | ANTELOPE | 5,118 | 36 km |
| 2021 | 13 MILE FIRE | 2,585 | 68 km |
| 2007 | W-RX-F SANDHILLS SUB UNIT B | 2,381 | 53 km |
| 2018 | MTMLR-FY18-RX-WUI DEEP LAKE | 2,088 | 50 km |
| 2021 | HIGHWAY 16 NORTH | 2,069 | 81 km |
| 2022 | MTMLR-FY22-RX-BRIDGERMAN | 1,852 | 49 km |
| 2023 | ROUTE 1 | 1,403 | 96 km |
| 2008 | NORTH SOUTH LAKE CREEK SU A | 1,367 | 43 km |
| 2011 | W-RX-F EAST ML BRIGERMANN | 1,197 | 51 km |
| 2023 | MTMLR-HFR-FY23-RX | 1,128 | 66 km |
| 2007 | H-RX-F BRIGERMANN 2007 | 1,043 | 50 km |
| 2022 | MTMLR-FY22-RX-NORTHSHORE | 1,015 | 50 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 9°F (-13°C) | 0.4 in | Coldest |
| February | 15°F (-9°C) | 0.4 in | Driest |
| March | 27°F (-3°C) | 0.6 in | |
| April | 43°F (6°C) | 1.1 in | |
| May | 55°F (13°C) | 2.1 in | |
| June | 64°F (18°C) | 2.6 in | Wettest |
| July | 67°F (20°C) | 2.3 in | |
| August | 68°F (20°C) | 1.8 in | Warmest |
| September | 56°F (14°C) | 1.4 in | |
| October | 44°F (7°C) | 0.8 in | |
| November | 26°F (-4°C) | 0.4 in | |
| December | 12°F (-11°C) | 0.5 in |
Westby has a seasonal temperature swing of 59°F / from 9°F in January to 68°F in August. Total annual precipitation is 14.2 inches, with June being the wettest month (2.6") and February the driest (0.4").