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Weather & Climate in Alta, CA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Alta experiences four distinct seasons with an average annual temperature of 52°F (11°C). Winters average 40°F in January while summers reach 70°F in July. The area gets 276 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 62.4 inches (wetter than the 38-inch national average). Air quality is rated Good with a median AQI of 48. The city sits at an elevation of 3,796 feet.
Temperature
40°F Jan (5°C)
70°F Jul (21°C)
| Annual Average | 52.2°F |
| 3% below US avg | |
| January Average | 40°F (5°C) |
| July Average | 70°F (21°C) |
| Sunny Days | 276 days/yr |
Geography
| Elevation | 3,796 ft (1,157 m) |
| Area | 2.4 sq mi (6.2 km²) |
| Population Density | 311/sq mi |
| Coordinates | 39.2157°N, 120.7985°W |
| Timezone | America/Los_Angeles |
| County | Nevada County County |
| Nearest Airport | Sacramento International (SMF) 56 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 48.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Moderate |
| Risk Score | 89.9 / 100 |
| Social Vulnerability | 43.5 / 100 |
| Community Resilience | 65.3 / 100 |
Hazard Breakdown
| Tornado | Very Low |
| Earthquake | Relatively Moderate |
| Wildfire | Relatively High |
| Flood | Relatively Moderate |
| Hail | Relatively Low |
| Strong Wind | Very Low |
| Heat Wave | Relatively Low |
| Winter Weather | Relatively Moderate |
| Lightning | Relatively Moderate |
| Drought | No Rating |
| Cold Wave | No Rating |
| Landslide | Relatively Moderate |
| Volcano | Very Low |
| Avalanche | Relatively High |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
2,680 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M6.1.
| Sep 12, 1994 | 4 km S of Carter Springs, Nevada | M6.1 | 108 km | 14 km |
| Jul 8, 2021 | Antelope Valley, CA | M6.0 | 137 km | 7 km |
| May 24, 2013 | 2 km NNE of Canyondam, California | M5.7 | 111 km | 8 km |
| May 11, 2023 | Lake Almanor Earthquake | M5.5 | 113 km | 6 km |
| Aug 10, 2001 | 3 km N of Blairsden, California | M5.2 | 68 km | 5 km |
| May 12, 2023 | 4km NW of Canyondam, CA | M5.2 | 112 km | 6 km |
| Sep 12, 1994 | 8 km ESE of Mesa Vista, California | M5.1 | 106 km | -1 km |
| Apr 26, 2008 | 1 km NW of Mogul, Nevada | M5.1 | 81 km | 3 km |
| Jul 8, 2021 | 32km SE of Markleeville, CA | M5.0 | 137 km | 7 km |
| Dec 22, 1995 | California-Nevada border region | M4.9 | 115 km | 4 km |
| May 24, 2013 | 1km NNW of Canyondam, CA | M4.9 | 110 km | 4 km |
| Dec 28, 1995 | 9 km WNW of Topaz Lake, Nevada | M4.8 | 114 km | -1 km |
| Apr 26, 2008 | 0 km N of Mogul, Nevada | M4.8 | 82 km | 3 km |
| Oct 30, 1998 | 4 km N of Tahoe Vista, California | M4.8 | 65 km | 1 km |
| Jun 26, 2005 | 8 km NNW of Tahoe Vista, California | M4.8 | 62 km | -2 km |
| Dec 23, 1995 | 8 km WNW of Topaz Lake, Nevada | M4.7 | 114 km | -1 km |
| May 7, 2021 | 19km NW of Truckee, CA | M4.7 | 50 km | 10 km |
| Jul 8, 2021 | 29km ENE of Dardanelle, CA | M4.6 | 136 km | 2 km |
| Dec 12, 1996 | 4 km SSW of Topaz Lake, Nevada | M4.6 | 123 km | -2 km |
| Jul 9, 2021 | 30km SE of Markleeville, CA | M4.6 | 135 km | 4 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
58 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF2. Total: 7 injuries.
| Date | Rating | Distance | Path | Fatalities |
| May 25, 2011 | EF2 | 83 km | 0.2 mi | 0 |
| Feb 10, 1994 | EF2 | 75 km | 0.3 mi | 0 |
| Feb 7, 1978 | EF2 | 80 km | 1.9 mi | 0 |
| Aug 15, 2020 | EF1 | 81 km | 0.1 mi | 0 |
| Aug 14, 2020 | EF1 | 81 km | 0.4 mi | 0 |
| Dec 24, 2015 | EF1 | 63 km | 6.2 mi | 0 |
| Oct 22, 2012 | EF1 | 32 km | 4.0 mi | 0 |
| Oct 22, 2012 | EF1 | 74 km | 2.0 mi | 0 |
| Oct 22, 2012 | EF1 | 65 km | 0.3 mi | 0 |
| Jan 8, 2005 | EF1 | 71 km | 0.1 mi | 0 |
| Jan 7, 1993 | EF1 | 83 km | 0.1 mi | 0 |
| Dec 17, 1992 | EF1 | 51 km | 5.0 mi | 0 |
| Dec 17, 1992 | EF1 | 75 km | 1.0 mi | 0 |
| Apr 19, 1988 | EF1 | 68 km | 1.0 mi | 0 |
| Mar 22, 1983 | EF1 | 73 km | 2.0 mi | 0 |
| Mar 23, 1978 | EF1 | 94 km | 0.1 mi | 0 |
| Jul 16, 1973 | EF1 | 98 km | 1.0 mi | 0 |
| Jun 28, 1970 | EF1 | 88 km | 2.3 mi | 0 |
| Nov 18, 2020 | EF0 | 81 km | 0.5 mi | 0 |
| Nov 18, 2020 | EF0 | 67 km | 4.4 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Nearby Volcanoes
3 volcanoes within 200 km. Closest: Lassen Volcanic Center (154 km).
| Name | Type | Elevation | Last Eruption | Distance |
| Lassen Volcanic Center | Stratovolcano | 3,187 m (10,456 ft) | 1917 | 154 km |
| Soda Lakes | Maar(s) | 1,251 m (4,104 ft) | Unknown | 169 km |
| Clear Lake | Volcanic field | 1,439 m (4,721 ft) | Unknown | 172 km |
Source: Smithsonian Institution Global Volcanism Program (GVP).
Wildfire History
20 wildfires (100+ acres) recorded within 100 km. Largest: NORTH COMPLEX (316,556 acres, 2020).
| Year | Name | Acres Burned | Distance |
| 2020 | NORTH COMPLEX | 316,556 | 63 km |
| 2021 | CALDOR | 226,583 | 70 km |
| 2018 | CAMP | 153,687 | 89 km |
| 2021 | SUGAR | 108,368 | 98 km |
| 2014 | KING | 99,070 | 39 km |
| 2022 | MOSQUITO | 77,858 | 22 km |
| 2019 | WALKER | 58,747 | 99 km |
| 2008 | BTU LIGHTNING COMPLEX (LONG BRANCH-JACK) | 52,091 | 90 km |
| 2000 | STORRIE | 49,588 | 99 km |
| 1994 | COTTONWOOD | 47,912 | 67 km |
| 2020 | LOYALTON | 45,484 | 80 km |
| 1988 | 49R | 36,673 | 35 km |
| 1999 | MHRD COMPLEX (BUCKS) | 34,459 | 87 km |
| 2020 | NORTH | 34,120 | 99 km |
| 2013 | AMERICAN | 27,938 | 20 km |
| 2008 | CANYON COMPLEX (SCOTCH) | 26,418 | 66 km |
| 2008 | HUMBOLDT | 23,769 | 93 km |
| 1992 | CLEVELAND | 21,835 | 53 km |
| 2008 | AMERICAN RIVER COMPLEX (GOVERNMENT) | 20,709 | 18 km |
| 2004 | POWER | 17,266 | 91 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 40°F (5°C) | 11.5 in | Wettest |
| February | 41°F (5°C) | 9.3 in | |
| March | 42°F (6°C) | 8.6 in | |
| April | 47°F (8°C) | 4.4 in | |
| May | 54°F (12°C) | 2.2 in | |
| June | 61°F (16°C) | 0.8 in | |
| July | 70°F (21°C) | 0.2 in | Warmest, Driest |
| August | 69°F (21°C) | 0.4 in | |
| September | 64°F (18°C) | 1.1 in | |
| October | 57°F (14°C) | 3.4 in | |
| November | 46°F (8°C) | 8.3 in | |
| December | 40°F (5°C) | 9.7 in | Coldest |
Alta has a seasonal temperature swing of 30°F / from 40°F in December to 70°F in July. Total annual precipitation is 59.9 inches, with January being the wettest month (11.5") and July the driest (0.2").