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Weather & Climate in Johnstown, WY
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Johnstown has a cool climate with an average annual temperature of 45°F (7°C). Winters average 22°F in January while summers reach 70°F in July. The area gets 310 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 8.8 inches (drier than the 38-inch national average). The area receives 28.4 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 34. The city sits at an elevation of 5,237 feet.
Temperature
22°F Jan (-6°C)
70°F Jul (21°C)
| Annual Average | 45.0°F |
| 17% below US avg | |
| January Average | 22°F (-6°C) |
| July Average | 70°F (21°C) |
| Sunny Days | 310 days/yr |
Geography
| Elevation | 5,237 ft (1,596 m) |
| Area | 32.2 sq mi (83.3 km²) |
| Population Density | 7/sq mi |
| Coordinates | 43.1138°N, 108.6899°W |
| Timezone | America/Denver |
| County | Fremont County County |
| Nearest Airport | Central Wyoming Regional (RIW) 12 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 34.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 59.7 / 100 |
| Social Vulnerability | 52.8 / 100 |
| Community Resilience | 11.8 / 100 |
Hazard Breakdown
| Tornado | Very Low |
| Earthquake | Relatively Low |
| Wildfire | Relatively Moderate |
| Flood | Relatively Low |
| Hail | Relatively Low |
| Strong Wind | Relatively Low |
| Heat Wave | Very Low |
| Winter Weather | Relatively Moderate |
| Lightning | Relatively High |
| Ice Storm | Very Low |
| Drought | Relatively Low |
| Cold Wave | Relatively Moderate |
| Landslide | Relatively Moderate |
| Volcano | Very Low |
| Avalanche | Relatively Moderate |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
118 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M5.0.
| Jan 7, 2004 | 20 km ESE of Kelly, Wyoming | M5.0 | 146 km | 3 km |
| Sep 21, 2013 | 20 km W of Fort Washakie, Wyoming | M4.8 | 39 km | 76 km |
| Aug 5, 2010 | 19 km E of Kelly, Wyoming | M4.8 | 148 km | 5 km |
| Aug 27, 2016 | 4 km ENE of Bondurant, Wyoming | M4.8 | 136 km | 12 km |
| Dec 28, 1993 | 38 km NE of Bondurant, Wyoming | M4.7 | 124 km | 8 km |
| Sep 27, 2001 | 35 km WSW of Dubois, Wyoming | M4.3 | 117 km | 5 km |
| Aug 5, 2010 | 19 km E of Kelly, Wyoming | M4.2 | 149 km | 5 km |
| Aug 17, 2010 | 22 km E of Kelly, Wyoming | M4.1 | 144 km | 5 km |
| Nov 3, 2017 | 57 km S of Ten Sleep, Wyoming | M4.0 | 115 km | 17 km |
| Feb 26, 2016 | 23 km SE of Kelly, Wyoming | M4.0 | 144 km | 5 km |
| Apr 7, 2004 | 18 km E of Kelly, Wyoming | M4.0 | 148 km | 5 km |
| Jan 7, 2004 | 18 km ESE of Kelly, Wyoming | M4.0 | 148 km | 5 km |
| Jan 7, 2004 | 17 km E of Kelly, Wyoming | M4.0 | 149 km | 5 km |
| Oct 10, 1992 | 25 km SSE of Riverton, Wyoming | M4.0 | 49 km | 5 km |
| May 26, 2000 | 5 km S of Bairoil, Wyoming | M4.0 | 137 km | 5 km |
| Apr 13, 2021 | 51 km S of Ten Sleep, Wyoming | M3.9 | 118 km | 12 km |
| Oct 3, 2000 | 22 km E of Kelly, Wyoming | M3.9 | 144 km | 7 km |
| Apr 1, 2011 | 22 km NW of Daniel, Wyoming | M3.9 | 129 km | 5 km |
| Nov 26, 1993 | 36 km NNE of Bondurant, Wyoming | M3.8 | 128 km | 5 km |
| Feb 12, 2023 | 20 km ESE of Kelly, Wyoming | M3.7 | 146 km | 8 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
26 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF3. Total: 4 injuries.
| Date | Rating | Distance | Path | Fatalities |
| Jun 16, 1962 | EF3 | 22 km | 0.5 mi | 0 |
| Jul 10, 2001 | EF2 | 88 km | 0.5 mi | 0 |
| Jun 7, 1986 | EF2 | 48 km | 2.0 mi | 0 |
| Aug 27, 1973 | EF2 | 61 km | 0.5 mi | 0 |
| Jun 6, 1967 | EF2 | 28 km | 8.2 mi | 0 |
| May 6, 2014 | EF1 | 35 km | 1.5 mi | 0 |
| Jun 6, 1997 | EF1 | 34 km | 2.0 mi | 0 |
| Aug 3, 1980 | EF1 | 48 km | 0.1 mi | 0 |
| Aug 3, 1976 | EF1 | 67 km | 0.1 mi | 0 |
| Jun 6, 1968 | EF1 | 24 km | 3.0 mi | 0 |
| Jun 5, 1968 | EF1 | 25 km | 0.1 mi | 0 |
| Jun 14, 1967 | EF1 | 30 km | 0.5 mi | 0 |
| Apr 23, 1964 | EF1 | 10 km | 0.5 mi | 0 |
| Sep 9, 2024 | EF0 | 71 km | 0.2 mi | 0 |
| Aug 11, 2020 | EF0 | 11 km | 0.2 mi | 0 |
| May 28, 2018 | EF0 | 87 km | 0.5 mi | 0 |
| Jun 3, 2014 | EF0 | 74 km | 2.2 mi | 0 |
| May 6, 2014 | EF0 | 28 km | 4.8 mi | 0 |
| Jun 14, 2009 | EF0 | 70 km | 0.7 mi | 0 |
| May 29, 2008 | EF0 | 66 km | 0.3 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
20 wildfires (100+ acres) recorded within 100 km. Largest: KATESBASIN (141,128 acres, 2000).
| Year | Name | Acres Burned | Distance |
| 2000 | KATESBASIN | 141,128 | 50 km |
| 2012 | ALPINE LAKE | 39,158 | 49 km |
| 1988 | FAYETTE | 29,234 | 76 km |
| 2008 | NEW FORK | 14,481 | 95 km |
| 2002 | SOUTH FORK II | 13,803 | 35 km |
| 2002 | PASS CREEK | 13,724 | 53 km |
| 1996 | FAYETTE | 5,308 | 90 km |
| 2000 | MUDDYCRK | 4,601 | 62 km |
| 2000 | MIDDLECREE | 4,534 | 94 km |
| 1996 | ANTLER | 4,492 | 95 km |
| 2007 | COPPER MTN. | 4,458 | 65 km |
| 2018 | ZIMMERMAN | 3,655 | 93 km |
| 2001 | RENNER DRA | 3,627 | 99 km |
| 1999 | LOWER GRAS | 3,489 | 87 km |
| 1989 | ANNS | 3,298 | 66 km |
| 1998 | LARSEN 1 | 3,157 | 94 km |
| 2002 | DIVIDE | 2,831 | 69 km |
| 2023 | BLACK MOUNTAIN | 2,596 | 100 km |
| 2000 | MDL ENOS | 2,593 | 92 km |
| 2018 | POTTER BUTTE | 2,444 | 97 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 22°F (-6°C) | 0.3 in | |
| February | 25°F (-4°C) | 0.2 in | Driest |
| March | 35°F (2°C) | 0.5 in | |
| April | 43°F (6°C) | 1.2 in | |
| May | 53°F (11°C) | 1.8 in | Wettest |
| June | 63°F (17°C) | 1.0 in | |
| July | 70°F (21°C) | 0.8 in | Warmest |
| August | 68°F (20°C) | 0.6 in | |
| September | 57°F (14°C) | 0.9 in | |
| October | 45°F (7°C) | 0.8 in | |
| November | 30°F (-1°C) | 0.5 in | |
| December | 20°F (-7°C) | 0.3 in | Coldest |
Johnstown has a seasonal temperature swing of 50°F / from 20°F in December to 70°F in July. Total annual precipitation is 8.9 inches, with May being the wettest month (1.8") and February the driest (0.2").