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Weather & Climate in Rio Dell, CA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Rio Dell enjoys a temperate climate with an average annual temperature of 56°F (13°C). Winters average 50°F in January while summers reach 62°F in July / relatively mild seasonal variation. The area gets 275 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 47.7 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 648 feet.
Temperature
50°F Jan (10°C)
62°F Jul (17°C)
| Annual Average | 55.6°F |
| 3% above US avg | |
| January Average | 50°F (10°C) |
| July Average | 62°F (17°C) |
| Sunny Days | 275 days/yr |
Geography
| Elevation | 648 ft (198 m) |
| Area | 2.5 sq mi (6.4 km²) |
| Population Density | 1,359/sq mi |
| Coordinates | 40.4956°N, 124.1152°W |
| Timezone | America/Los_Angeles |
| County | Humboldt County County |
| Nearest Airport | Redding Regional (RDD) 95 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 48.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively High |
| Risk Score | 96.8 / 100 |
| Social Vulnerability | 74.7 / 100 |
| Community Resilience | 56.4 / 100 |
Hazard Breakdown
| Tornado | Very Low |
| Earthquake | Relatively High |
| Wildfire | Relatively Moderate |
| Flood | Relatively High |
| Hail | Very Low |
| Strong Wind | Very Low |
| Heat Wave | Relatively Low |
| Winter Weather | Very Low |
| Lightning | Relatively Low |
| Drought | Relatively Moderate |
| Cold Wave | No Rating |
| Landslide | Relatively High |
| Coastal Flood | Relatively High |
| Tsunami | Relatively High |
| Volcano | No Rating |
| Avalanche | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
5,520 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M7.2.
| Apr 25, 1992 | The 1992 Petrolia, California Earthquake | M7.2 | 20 km | 10 km |
| Sep 1, 1994 | 121 km W of Ferndale, California | M7.1 | 133 km | 10 km |
| Mar 10, 2014 | 77 km WNW of Indianola, California | M6.8 | 94 km | 16 km |
| Feb 19, 1995 | 126 km W of Ferndale, California | M6.6 | 139 km | 5 km |
| Apr 26, 1992 | 32 km SW of Ferndale, California | M6.6 | 39 km | 22 km |
| Jan 10, 2010 | The 2010 Eureka, California Earthquake | M6.5 | 52 km | 29 km |
| Apr 26, 1992 | 30 km WSW of Ferndale, California | M6.5 | 39 km | 19 km |
| Aug 17, 1991 | 30 km SSW of Scotia, California | M6.0 | 31 km | 8 km |
| Feb 4, 2010 | 61 km WSW of Ferndale, California | M5.9 | 72 km | 23 km |
| Mar 9, 2020 | 69km W of Petrolia, CA | M5.8 | 84 km | 3 km |
| Jan 28, 2015 | 40 km SW of Ferndale, California | M5.7 | 46 km | 17 km |
| Mar 16, 2000 | 85 km WSW of Ferndale, California | M5.7 | 96 km | 5 km |
| Sep 3, 2016 | 124 km WSW of Ferndale, California | M5.6 | 135 km | 29 km |
| Jan 22, 1997 | 33 km SW of Scotia, California | M5.6 | 33 km | 23 km |
| Feb 13, 2012 | 26 km NNW of Willow Creek, California | M5.6 | 77 km | 27 km |
| Jun 23, 2019 | 6km SSW of Petrolia, CA | M5.6 | 29 km | 9 km |
| May 21, 2023 | 108km W of Petrolia, CA | M5.6 | 123 km | 10 km |
| Oct 4, 1997 | 100 km WNW of Samoa, California | M5.5 | 121 km | 7 km |
| Nov 27, 1998 | 87 km W of Ferndale, California | M5.4 | 101 km | 4 km |
| Feb 26, 2007 | 51 km W of Ferndale, California | M5.4 | 65 km | -1 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
2 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF2.
| Date | Rating | Distance | Path | Fatalities |
| Mar 29, 1958 | EF2 | 51 km | 2.0 mi | 0 |
| Jan 25, 2018 | EF0 | 35 km | 0.0 mi | 0 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Tsunami History
3 tsunamis recorded within 500 km. Highest wave on record: 1.8 m (6 ft).
| Year | Location | Cause | Max Wave | Deaths | Distance |
| 1992 | CAPE MENDOCINO, N. CALIFORNIA | Earthquake | 1.8 m | — | 22 km |
| 2024 | CAPE MENDOCINO, N. CALIFORNIA | Earthquake | 0.1 m | — | 78 km |
| 1994 | N. CALIFORNIA | Earthquake | 0.1 m | — | 133 km |
Source: NOAA/NCEI Historical Tsunami Database.
Nearby Volcanoes
1 volcano within 200 km. Closest: Shasta (191 km).
| Name | Type | Elevation | Last Eruption | Distance |
| Shasta | Stratovolcano | 4,317 m (14,163 ft) | 1250 | 191 km |
Source: Smithsonian Institution Global Volcanism Program (GVP).
Wildfire History
20 wildfires (100+ acres) recorded within 100 km. Largest: MONUMENT (226,125 acres, 2021).
| Year | Name | Acres Burned | Distance |
| 2021 | MONUMENT | 226,125 | 76 km |
| 2020 | RED SALMON COMPLEX | 147,535 | 91 km |
| 1999 | MEGRAM- ORLEANS | 125,337 | 83 km |
| 2006 | PIGEON | 100,962 | 92 km |
| 2015 | RIVER COMPLEX | 78,531 | 79 km |
| 2015 | ROUTE COMPLEX | 35,444 | 50 km |
| 2008 | IRON AND ALPS COMPLEXES (EAGLE) | 32,397 | 84 km |
| 2015 | PATTISON | 31,129 | 63 km |
| 2022 | CAMPBELL | 30,392 | 69 km |
| 2008 | IRON AND ALPS COMPLEXES (BUCKHORN) | 29,446 | 81 km |
| 2008 | LIME COMPLEX (LIME) | 27,234 | 60 km |
| 2008 | LIME COMPLEX (MINERS) | 25,680 | 73 km |
| 2008 | IRON AND ALPS COMPLEXES (CEDAR) | 25,277 | 70 km |
| 2015 | SHIELL | 24,830 | 89 km |
| 2015 | LASSICS | 20,716 | 53 km |
| 2017 | HELENA | 18,709 | 94 km |
| 1999 | BIG BAR COMPLEX (ONION) | 16,742 | 75 km |
| 2008 | HELLS HALF FIRE (HALF) | 14,873 | 56 km |
| 1987 | COLD | 14,801 | 61 km |
| 2017 | BUCK | 13,612 | 97 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 50°F (10°C) | 11.5 in | |
| February | 46°F (8°C) | 9.7 in | |
| March | 46°F (8°C) | 9.4 in | |
| April | 48°F (9°C) | 4.9 in | |
| May | 52°F (11°C) | 1.9 in | |
| June | 57°F (14°C) | 0.6 in | |
| July | 62°F (17°C) | 0.2 in | Driest |
| August | 62°F (17°C) | 0.7 in | Warmest |
| September | 61°F (16°C) | 1.3 in | |
| October | 55°F (13°C) | 4.5 in | |
| November | 48°F (9°C) | 11.2 in | |
| December | 44°F (7°C) | 12.1 in | Coldest, Wettest |
Rio Dell has a seasonal temperature swing of 18°F / from 44°F in December to 62°F in August. Total annual precipitation is 67.8 inches, with December being the wettest month (12.1") and July the driest (0.2").