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Port Costa, CA
Full City Profile · California · Marin County County
1.8
/5.0
D
Poor
194
Population
1,213/sq mi density
$586,500
Home Value
$653,802 Zillow
62°F
Avg Temperature
326 sunny days/yr
94
Violent Crime/100K
1,743 property/100K
D
Overall
1.8 / 5.0
Below average overall score based on economy, affordability, safety and education
F
Safety
1.0 / 5.0
94 violent crimes/100K
C+
Education
2.5 / 5.0
19.1% bachelor's degree or higher
Port Costa enjoys a temperate climate with an average annual temperature of 62°F (17°C). Winters average 50°F in January while summers reach 71°F in July. The area gets 326 sunny days per year. Annual precipitation totals 21.5 inches. Air quality is rated Good with a median AQI of 48.
Temperature
50°F Jan (10°C)
71°F Jul (21°C)
| Annual Average | 61.6°F |
| 14% above US avg | |
| January Average | 50°F (10°C) |
| July Average | 71°F (21°C) |
| Sunny Days | 326 days/yr |
Geography
| Elevation | 171 ft (52 m) |
| Area | 0.2 sq mi (0.4 km²) |
| Population Density | 1,213/sq mi |
| Coordinates | 38.0445°N, 122.1849°W |
| Timezone | America/Los_Angeles |
| County | Marin County County |
| Nearest Airport | Metro Oakland International (OAK) 22 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 48.0 |
| Rating | Good |
Air Pollutants (EPA 2023)
| Ozone (O₃) | 0.0326 ppm |
| NO₂ (Nitrogen Dioxide) | 9.1 ppb |
| CO (Carbon Monoxide) | 0.31 ppm |
| PM2.5 (Fine Particles) | 5.4 μg/m³ |
Natural Hazard Risk
| Overall Risk | Relatively High |
| Risk Score | 96.4 / 100 |
| Social Vulnerability | 24.7 / 100 |
| Community Resilience | 99.2 / 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 Low |
| Cold Wave | No Rating |
| Landslide | Relatively High |
| Coastal Flood | Very High |
| Tsunami | Relatively Moderate |
| Volcano | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Tsunami History
5 tsunamis recorded within 500 km. Highest wave on record: 4.5 m (15 ft).
| Year | Location | Cause | Max Wave | Deaths | Distance |
| 1868 | N. CALIFORNIA | Eruption + Earthquake | 4.5 m | 30 | 39 km |
| 1989 | N. CALIFORNIA | Earthquake | 1.0 m | 62 | 115 km |
| 1856 | N. CALIFORNIA | Eruption + Earthquake | 0.6 m | — | 61 km |
| 1906 | N. CALIFORNIA | Eruption + Earthquake | 0.1 m | — | 47 km |
| 1865 | N. CALIFORNIA | Eruption + Earthquake | — | — | 97 km |
Source: NOAA/NCEI Historical Tsunami Database. Sorted by wave height.
Nearby Volcanoes
1 volcano within 200 km. Closest: Clear Lake (115 km).
| Name | Type | Elevation | Last Eruption | Distance |
| Clear Lake | Volcanic field | 1,439 m (4,721 ft) | Unknown | 115 km |
Source: Smithsonian Institution Global Volcanism Program (GVP). Sorted by distance.
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 50°F (10°C) | 5.8 in | Wettest |
| February | 52°F (11°C) | 4.9 in | |
| March | 54°F (12°C) | 3.9 in | |
| April | 58°F (14°C) | 1.4 in | |
| May | 63°F (17°C) | 0.6 in | |
| June | 68°F (20°C) | 0.2 in | |
| July | 71°F (21°C) | 0.0 in | Warmest, Driest |
| August | 71°F (21°C) | 0.1 in | |
| September | 69°F (20°C) | 0.3 in | |
| October | 63°F (17°C) | 1.5 in | |
| November | 54°F (12°C) | 3.9 in | |
| December | 47°F (8°C) | 4.2 in | Coldest |
Port Costa has a seasonal temperature swing of 23°F / from 47°F in December to 71°F in July. Total annual precipitation is 26.7 inches, with January being the wettest month (5.8") and July the driest (0.0").