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Weather & Climate in Lewistown, MT
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Lewistown has a cool climate with an average annual temperature of 43°F (6°C). Winters average 24°F in January while summers reach 66°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 17.2 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 4,122 feet.
Temperature
24°F Jan (-5°C)
66°F Jul (19°C)
| Annual Average | 43.1°F |
| 20% below US avg | |
| January Average | 24°F (-5°C) |
| July Average | 66°F (19°C) |
| Sunny Days | 273 days/yr |
Geography
| Elevation | 4,122 ft (1,256 m) |
| Area | 5.7 sq mi (14.8 km²) |
| Population Density | 1,054/sq mi |
| Coordinates | 47.0514°N, 109.4524°W |
| Timezone | America/Denver |
| County | Fergus County County |
| Nearest Airport | Great Falls International (GTF) 95 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 26.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 45.1 / 100 |
| Social Vulnerability | 45.2 / 100 |
| Community Resilience | 70.3 / 100 |
Hazard Breakdown
| Tornado | Very Low |
| Earthquake | Very Low |
| Wildfire | Relatively Low |
| Flood | Relatively Low |
| Hail | Very Low |
| Strong Wind | Very Low |
| Heat Wave | Very Low |
| Winter Weather | Relatively High |
| Lightning | Relatively Moderate |
| Ice Storm | Very Low |
| Drought | Relatively Low |
| Cold Wave | Relatively High |
| Landslide | Relatively Low |
| Avalanche | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
11 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M3.7.
| Jan 9, 2003 | 23 km E of Wilsall, Montana | M3.7 | 134 km | 11 km |
| Jul 15, 2006 | Western Montana | M3.0 | 141 km | 10 km |
| Dec 5, 1991 | 15 km WSW of Hays, Montana | M3.0 | 109 km | 10 km |
| Sep 15, 2012 | 23 km SSW of White Sulphur Springs, Montana | M2.9 | 144 km | 8 km |
| Aug 25, 2012 | 28 km S of White Sulphur Springs, Montana | M2.8 | 142 km | 10 km |
| Jul 15, 2006 | 28 km S of White Sulphur Springs, Montana | M2.8 | 141 km | 10 km |
| Nov 4, 2017 | 32 km NE of Wilsall, Montana | M2.7 | 119 km | 4 km |
| Oct 16, 2011 | Eastern Montana | M2.7 | 90 km | 21 km |
| Aug 17, 2012 | 28 km S of White Sulphur Springs, Montana | M2.5 | 142 km | 9 km |
| Jan 8, 2003 | 24 km E of Wilsall, Montana | M2.5 | 134 km | 14 km |
| Jul 15, 2015 | 48 km E of Zortman, Montana | M2.5 | 150 km | 23 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
64 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF3. Total: 6 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Jul 5, 1988 | EF3 | 98 km | 10.0 mi | 0 |
| Jul 5, 1988 | EF3 | 80 km | 3.0 mi | 0 |
| Jul 8, 2002 | EF2 | 23 km | 10.0 mi | 0 |
| Aug 14, 1999 | EF2 | 3 km | 5.0 mi | 0 |
| Jun 25, 1996 | EF2 | 47 km | 2.0 mi | 0 |
| Apr 24, 1994 | EF2 | 63 km | 1.5 mi | 0 |
| Apr 24, 1994 | EF2 | 63 km | 1.0 mi | 0 |
| May 28, 1981 | EF2 | 45 km | 1.5 mi | 0 |
| Jun 8, 1976 | EF2 | 58 km | 0.1 mi | 0 |
| Jul 10, 1965 | EF2 | 77 km | 2.0 mi | 0 |
| Jul 20, 1964 | EF2 | 77 km | 2.0 mi | 0 |
| Aug 7, 1962 | EF2 | 84 km | 2.0 mi | 0 |
| Jun 16, 2007 | EF1 | 86 km | 5.3 mi | 0 |
| Apr 22, 2003 | EF1 | 60 km | 2.0 mi | 0 |
| Aug 23, 1998 | EF1 | 17 km | 3.5 mi | 0 |
| May 10, 1977 | EF1 | 43 km | 0.1 mi | 0 |
| May 10, 1977 | EF1 | 48 km | 0.1 mi | 0 |
| Jun 3, 1971 | EF1 | 56 km | 2.3 mi | 0 |
| Jul 7, 1957 | EF1 | 43 km | 1.5 mi | 0 |
| Jul 6, 2022 | EF0 | 63 km | 1.3 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
20 wildfires (100+ acres) recorded within 100 km. Largest: TURKEY (25,658 acres, 1990).
| Year | Name | Acres Burned | Distance |
| 1990 | TURKEY | 25,658 | 60 km |
| 2021 | TAYLOR | 21,704 | 52 km |
| 2021 | SOUTH MOCCASIN | 12,727 | 16 km |
| 2009 | MEISSNER | 12,318 | 75 km |
| 1985 | SANDPOINT | 10,439 | 84 km |
| 2020 | LOUSE CREEK | 5,237 | 28 km |
| 1999 | HORSE THIE | 4,767 | 80 km |
| 1991 | BURNETTEPK | 4,644 | 15 km |
| 2015 | TROPHY RIDGE | 4,478 | 89 km |
| 2020 | YOGO | 4,429 | 82 km |
| 2020 | EAGLE ROCK ROAD | 3,129 | 89 km |
| 2012 | SKINNER | 3,097 | 88 km |
| 2012 | ANDERSON | 2,917 | 68 km |
| 2020 | LODE ROAD | 2,736 | 62 km |
| 2001 | TWIN COULE | 2,688 | 45 km |
| 2008 | GOLDEN VALLEY COMPLEX | 2,621 | 88 km |
| 2001 | LOST FORK-MONARCH COMPLEX (LOST FORK) | 2,313 | 92 km |
| 1999 | UNNAMED | 2,161 | 63 km |
| 2005 | KNOX | 2,060 | 69 km |
| 2021 | FOUR SISTERS | 1,999 | 80 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 24°F (-5°C) | 0.9 in | |
| February | 25°F (-4°C) | 0.6 in | Driest |
| March | 32°F (0°C) | 0.9 in | |
| April | 41°F (5°C) | 1.2 in | |
| May | 50°F (10°C) | 3.2 in | Wettest |
| June | 59°F (15°C) | 3.0 in | |
| July | 66°F (19°C) | 1.7 in | Warmest |
| August | 65°F (18°C) | 1.9 in | |
| September | 55°F (13°C) | 1.5 in | |
| October | 45°F (7°C) | 1.1 in | |
| November | 31°F (-1°C) | 0.7 in | |
| December | 23°F (-5°C) | 0.8 in | Coldest |
Lewistown has a seasonal temperature swing of 43°F / from 23°F in December to 66°F in July. Total annual precipitation is 17.6 inches, with May being the wettest month (3.2") and February the driest (0.6").