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Weather & Climate in Arco, ID
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Arco has a cool climate with an average annual temperature of 44°F (7°C). Winters average 19°F in January while summers reach 69°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 23.8 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 33. The city sits at an elevation of 5,315 feet.
Temperature
19°F Jan (-7°C)
69°F Jul (21°C)
| Annual Average | 43.7°F |
| 19% below US avg | |
| January Average | 19°F (-7°C) |
| July Average | 69°F (21°C) |
| Sunny Days | 310 days/yr |
Geography
| Elevation | 5,315 ft (1,620 m) |
| Area | 1.1 sq mi (2.8 km²) |
| Population Density | 787/sq mi |
| Coordinates | 43.6319°N, 113.3010°W |
| Timezone | America/Boise |
| County | Butte County County |
| Nearest Airport | Pocatello Regional (PIH) 61 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 33.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 4.4 / 100 |
| Social Vulnerability | 45.7 / 100 |
| Community Resilience | 13.2 / 100 |
Hazard Breakdown
| Tornado | Very Low |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Very Low |
| Hail | Very Low |
| Strong Wind | Very Low |
| Heat Wave | Very Low |
| Winter Weather | Relatively Low |
| Lightning | Very Low |
| Ice Storm | Very Low |
| Drought | Very Low |
| Cold Wave | Relatively Low |
| Landslide | Very Low |
| Volcano | Very Low |
| Avalanche | Relatively Moderate |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
532 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M5.1.
| Aug 20, 1999 | 22 km NW of Lima, Montana | M5.1 | 135 km | 16 km |
| Jan 3, 2015 | 9 km E of Challis, Idaho | M5.0 | 117 km | 9 km |
| Apr 13, 2014 | 15 km NNW of Challis, Idaho | M4.8 | 137 km | 4 km |
| Jun 7, 1994 | 18 km E of Challis, Idaho | M4.8 | 111 km | 5 km |
| Apr 9, 2019 | 9 km NE of Lima, Montana | M4.6 | 134 km | 14 km |
| May 4, 1992 | 20 km E of Challis, Idaho | M4.6 | 112 km | 10 km |
| Dec 28, 1991 | southern Idaho | M4.4 | 122 km | 5 km |
| Apr 5, 2011 | 28 km NNE of Spencer, Idaho | M4.4 | 146 km | 12 km |
| Apr 14, 2014 | 13 km NW of Challis, Idaho | M4.4 | 135 km | 7 km |
| May 6, 1992 | 17 km E of Challis, Idaho | M4.4 | 110 km | 5 km |
| Mar 22, 1992 | 11 km NE of Challis, Idaho | M4.3 | 126 km | 5 km |
| Jun 8, 2025 | 24 km E of Clayton, Idaho | M4.3 | 95 km | 7 km |
| Jan 27, 2025 | 26 km NW of Clayton, Idaho | M4.2 | 139 km | 9 km |
| Jul 14, 2023 | 3 km S of Lima, Montana | M4.2 | 122 km | 12 km |
| Aug 13, 1998 | 3 km ESE of Challis, Idaho | M4.2 | 119 km | 5 km |
| Jun 7, 1994 | 21 km E of Challis, Idaho | M4.1 | 114 km | 5 km |
| Apr 10, 2014 | 11 km NW of Challis, Idaho | M4.0 | 134 km | 7 km |
| Aug 3, 1996 | 7 km E of Challis, Idaho | M4.0 | 119 km | 5 km |
| Jun 23, 1992 | 10 km NE of Clayton, Idaho | M4.0 | 112 km | 10 km |
| Aug 26, 1999 | 21 km NW of Lima, Montana | M4.0 | 135 km | 12 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: EF1. Total: 2 injuries.
| Date | Rating | Distance | Path | Fatalities |
| May 31, 2018 | EF1 | 47 km | 12.0 mi | 0 |
| Jun 1, 2002 | EF1 | 93 km | 2.5 mi | 0 |
| Feb 14, 2000 | EF1 | 83 km | 14.0 mi | 0 |
| Feb 14, 2000 | EF1 | 99 km | 9.0 mi | 0 |
| Jul 20, 1999 | EF1 | 94 km | 2.5 mi | 0 |
| May 31, 1997 | EF1 | 68 km | 4.0 mi | 0 |
| May 21, 1992 | EF1 | 10 km | 0.2 mi | 0 |
| Apr 17, 1988 | EF1 | 94 km | 2.0 mi | 0 |
| Mar 23, 1988 | EF1 | 95 km | 15.0 mi | 0 |
| Jul 21, 1987 | EF1 | 90 km | 0.2 mi | 0 |
| Jul 18, 1987 | EF1 | 26 km | 1.0 mi | 0 |
| Aug 24, 1986 | EF1 | 97 km | 0.5 mi | 0 |
| Jul 27, 1972 | EF1 | 54 km | 1.0 mi | 0 |
| May 26, 1964 | EF1 | 99 km | 0.5 mi | 0 |
| May 18, 1956 | EF1 | 87 km | 0.1 mi | 0 |
| May 26, 2019 | EF0 | 86 km | 1.8 mi | 0 |
| Jun 21, 2018 | EF0 | 31 km | 5.1 mi | 0 |
| May 31, 2018 | EF0 | 62 km | 3.0 mi | 0 |
| Apr 7, 2018 | EF0 | 68 km | 0.5 mi | 0 |
| Jul 11, 2015 | EF0 | 78 km | 7.4 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Nearby Volcanoes
4 volcanoes within 200 km. Closest: Craters of the Moon (29 km).
| Name | Type | Elevation | Last Eruption | Distance |
| Craters of the Moon | Pyroclastic cone(s) | 2,005 m (6,578 ft) | -130 | 29 km |
| Hell's Half Acre | Shield | 1,631 m (5,351 ft) | -3250 | 70 km |
| Wapi Lava Field | Shield | 1,604 m (5,262 ft) | -300 | 84 km |
| Black Butte Crater Lava Field | Shield | 1,478 m (4,849 ft) | -8400 | 99 km |
Source: Smithsonian Institution Global Volcanism Program (GVP).
Wildfire History
20 wildfires (100+ acres) recorded within 100 km. Largest: COXS WELL (219,424 acres, 1996).
| Year | Name | Acres Burned | Distance |
| 1996 | COXS WELL | 219,424 | 53 km |
| 2006 | CRYSTAL | 218,581 | 60 km |
| 1996 | RICHFIELDS | 178,385 | 83 km |
| 1992 | BLACK RIDGE | 147,833 | 74 km |
| 1999 | MULE BUTTE | 138,102 | 65 km |
| 2013 | BEAVER CREEK | 111,286 | 97 km |
| 2010 | JEFFERSON | 108,542 | 59 km |
| 2019 | SHEEP | 107,233 | 46 km |
| 2012 | FLAT TOP 2 | 102,340 | 84 km |
| 2000 | COFFEE POINT | 73,480 | 59 km |
| 2018 | SHARPS | 63,895 | 61 km |
| 2000 | FLATTOP | 56,792 | 74 km |
| 2017 | MAMMOTH CAVE | 50,391 | 90 km |
| 1999 | CEDAR BUTTE | 49,625 | 51 km |
| 2007 | CASTLE ROCK | 48,430 | 94 km |
| 2011 | T17 | 45,631 | 49 km |
| 2005 | RUPERT | 45,361 | 77 km |
| 1999 | INEEL FIRE | 43,547 | 56 km |
| 2016 | LAIDLAW | 40,551 | 57 km |
| 2003 | DEEP | 38,701 | 99 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 19°F (-7°C) | 1.0 in | Coldest |
| February | 22°F (-5°C) | 1.0 in | |
| March | 32°F (0°C) | 0.8 in | |
| April | 41°F (5°C) | 0.8 in | |
| May | 50°F (10°C) | 1.3 in | Wettest |
| June | 59°F (15°C) | 1.3 in | |
| July | 69°F (21°C) | 0.8 in | Warmest |
| August | 67°F (19°C) | 0.8 in | |
| September | 57°F (14°C) | 0.8 in | |
| October | 46°F (8°C) | 0.6 in | Driest |
| November | 32°F (-0°C) | 0.9 in | |
| December | 20°F (-7°C) | 1.1 in |
Arco has a seasonal temperature swing of 51°F / from 19°F in January to 69°F in July. Total annual precipitation is 11.0 inches, with May being the wettest month (1.3") and October the driest (0.6").