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Weather & Climate in Alta Sierra CDP (Nevada County), CA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Alta Sierra CDP (Nevada County) enjoys a temperate climate with an average annual temperature of 56°F (13°C). Winters average 43°F in January while summers reach 73°F in July. The area gets 290 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 53.2 inches (wetter than the 38-inch national average). The area receives 8.6 inches of snow annually. Air quality is rated Good with a median AQI of 48. The city sits at an elevation of 2,083 feet.
Temperature
43°F Jan (6°C)
73°F Jul (23°C)
| Annual Average | 56.1°F |
| 4% above US avg | |
| January Average | 43°F (6°C) |
| July Average | 73°F (23°C) |
| Sunny Days | 290 days/yr |
Geography
| Elevation | 2,083 ft (635 m) |
| Area | 8.3 sq mi (21.5 km²) |
| Population Density | 849/sq mi |
| Coordinates | 39.1262°N, 121.0491°W |
| Timezone | America/Los_Angeles |
| County | Yuba County County |
| Nearest Airport | Sacramento International (SMF) 42 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 48.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively Low |
| Risk Score | 80.9 / 100 |
| Social Vulnerability | 30.4 / 100 |
| Community Resilience | 36.6 / 100 |
Hazard Breakdown
| Tornado | Very Low |
| Earthquake | Relatively Low |
| Wildfire | Relatively Moderate |
| Flood | Relatively Moderate |
| Hail | Very Low |
| Strong Wind | Very Low |
| Heat Wave | Relatively Low |
| Winter Weather | Very Low |
| Lightning | Relatively Low |
| Drought | Relatively High |
| Cold Wave | No Rating |
| Landslide | Relatively Moderate |
| Volcano | Very Low |
| Avalanche | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
2,882 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 | 126 km | 14 km |
| Aug 24, 2014 | The 2014 South Napa, California Earthquake | M6.0 | 149 km | 11 km |
| May 24, 2013 | 2 km NNE of Canyondam, California | M5.7 | 119 km | 8 km |
| May 11, 2023 | Lake Almanor Earthquake | M5.5 | 120 km | 6 km |
| Aug 10, 2001 | 3 km N of Blairsden, California | M5.2 | 85 km | 5 km |
| May 12, 2023 | 4km NW of Canyondam, CA | M5.2 | 119 km | 6 km |
| Sep 12, 1994 | 8 km ESE of Mesa Vista, California | M5.1 | 123 km | -1 km |
| Apr 26, 2008 | 1 km NW of Mogul, Nevada | M5.1 | 105 km | 3 km |
| Sep 3, 2000 | 5 km WSW of Yountville, California | M4.9 | 145 km | 9 km |
| May 24, 2013 | 1km NNW of Canyondam, CA | M4.9 | 117 km | 4 km |
| Dec 22, 1995 | California-Nevada border region | M4.9 | 130 km | 4 km |
| Dec 28, 1995 | 9 km WNW of Topaz Lake, Nevada | M4.8 | 129 km | -1 km |
| Oct 30, 1998 | 4 km N of Tahoe Vista, California | M4.8 | 88 km | 1 km |
| Apr 26, 2008 | 0 km N of Mogul, Nevada | M4.8 | 106 km | 3 km |
| Jun 26, 2005 | 8 km NNW of Tahoe Vista, California | M4.8 | 85 km | -2 km |
| Dec 23, 1995 | 8 km WNW of Topaz Lake, Nevada | M4.7 | 130 km | -1 km |
| May 7, 2021 | 19km NW of Truckee, CA | M4.7 | 73 km | 10 km |
| Jul 8, 2021 | 29km ENE of Dardanelle, CA | M4.6 | 149 km | 2 km |
| Dec 12, 1996 | 4 km SSW of Topaz Lake, Nevada | M4.6 | 139 km | -2 km |
| Jul 9, 2021 | 30km SE of Markleeville, CA | M4.6 | 148 km | 4 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
61 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF2. Total: 6 injuries.
| Date | Rating | Distance | Path | Fatalities |
| May 25, 2011 | EF2 | 72 km | 0.2 mi | 0 |
| Feb 10, 1994 | EF2 | 63 km | 0.3 mi | 0 |
| Feb 7, 1978 | EF2 | 59 km | 1.9 mi | 0 |
| Dec 24, 2015 | EF1 | 47 km | 6.2 mi | 0 |
| Oct 22, 2012 | EF1 | 42 km | 0.3 mi | 0 |
| Oct 22, 2012 | EF1 | 10 km | 4.0 mi | 0 |
| Oct 22, 2012 | EF1 | 51 km | 2.0 mi | 0 |
| Jan 8, 2005 | EF1 | 58 km | 0.1 mi | 0 |
| Jan 7, 1993 | EF1 | 66 km | 0.1 mi | 0 |
| Dec 17, 1992 | EF1 | 36 km | 5.0 mi | 0 |
| Dec 17, 1992 | EF1 | 63 km | 1.0 mi | 0 |
| Apr 19, 1988 | EF1 | 51 km | 1.0 mi | 0 |
| Mar 22, 1983 | EF1 | 52 km | 2.0 mi | 0 |
| Mar 23, 1978 | EF1 | 87 km | 0.1 mi | 0 |
| Jun 28, 1970 | EF1 | 69 km | 2.3 mi | 0 |
| Jan 14, 2023 | EF0 | 90 km | 0.3 mi | 0 |
| Nov 8, 2022 | EF0 | 92 km | 0.8 mi | 0 |
| Nov 18, 2020 | EF0 | 55 km | 4.4 mi | 0 |
| Nov 18, 2020 | EF0 | 73 km | 0.5 mi | 0 |
| May 18, 2020 | EF0 | 81 km | 0.1 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Nearby Volcanoes
3 volcanoes within 200 km. Closest: Clear Lake (150 km).
| Name | Type | Elevation | Last Eruption | Distance |
| Clear Lake | Volcanic field | 1,439 m (4,721 ft) | Unknown | 150 km |
| Lassen Volcanic Center | Stratovolcano | 3,187 m (10,456 ft) | 1917 | 157 km |
| Soda Lakes | Maar(s) | 1,251 m (4,104 ft) | Unknown | 193 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 | 67 km |
| 2021 | CALDOR | 226,583 | 79 km |
| 2018 | CAMP | 153,687 | 82 km |
| 2014 | KING | 99,070 | 49 km |
| 2022 | MOSQUITO | 77,858 | 32 km |
| 2008 | BTU LIGHTNING COMPLEX (LONG BRANCH-JACK) | 52,091 | 88 km |
| 1994 | COTTONWOOD | 47,912 | 91 km |
| 1988 | 49R | 36,673 | 19 km |
| 1999 | MHRD COMPLEX (BUCKS) | 34,459 | 87 km |
| 2013 | AMERICAN | 27,938 | 40 km |
| 2008 | CANYON COMPLEX (SCOTCH) | 26,418 | 67 km |
| 2008 | HUMBOLDT | 23,769 | 84 km |
| 1992 | CLEVELAND | 21,835 | 63 km |
| 2008 | AMERICAN RIVER COMPLEX (GOVERNMENT) | 20,709 | 40 km |
| 2004 | POWER | 17,266 | 96 km |
| 2001 | STAR | 16,846 | 48 km |
| 1999 | MUSTY | 16,846 | 99 km |
| 2017 | CASCADE | 16,155 | 38 km |
| 2001 | MARTIS | 14,526 | 94 km |
| 2006 | ZAM ASSIST | 14,404 | 85 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 43°F (6°C) | 7.8 in | Coldest, Wettest |
| February | 48°F (9°C) | 6.6 in | |
| March | 50°F (10°C) | 6.5 in | |
| April | 55°F (13°C) | 3.0 in | |
| May | 62°F (17°C) | 1.1 in | |
| June | 69°F (21°C) | 0.4 in | |
| July | 73°F (23°C) | 0.1 in | Driest |
| August | 75°F (24°C) | 0.2 in | Warmest |
| September | 70°F (21°C) | 0.8 in | |
| October | 62°F (16°C) | 2.6 in | |
| November | 50°F (10°C) | 6.5 in | |
| December | 45°F (7°C) | 6.6 in |
Alta Sierra CDP (Nevada County) has a seasonal temperature swing of 31°F / from 43°F in January to 75°F in August. Total annual precipitation is 42.1 inches, with January being the wettest month (7.8") and July the driest (0.1").