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Alum Rock, CA
Full City Profile · California · Santa Clara County County
2.7
/5.0
C+
Fair
11,619
Population
13,355/sq mi density
$111,976
Median Income
$34,255 per capita
$880,000
Home Value
$1,435,993 Zillow
$2,412
Median Rent
36.2% income on rent
62°F
Avg Temperature
330 sunny days/yr
321
Violent Crime/100K
2,434 property/100K
C+
Overall
2.7 / 5.0
Fair overall score based on economy, affordability, safety and education
A+
Economy
4.8 / 5.0
$111,976 median income, 3.1% unemployment
C
Affordability
2.2 / 5.0
$880,000 home value, $2,412/mo rent
F
Safety
1.0 / 5.0
321 violent crimes/100K
C+
Education
2.6 / 5.0
19.8% bachelor's degree or higher
Alum Rock enjoys a temperate climate with an average annual temperature of 62°F (17°C). Winters average 51°F in January while summers reach 71°F in July. The area gets 330 sunny days per year. Annual precipitation totals 16.1 inches. The area receives 0.0 inches of snow annually. Air quality is rated Good with a median AQI of 48.
Temperature
51°F Jan (11°C)
71°F Jul (21°C)
| Annual Average | 61.5°F |
| 14% above US avg | |
| January Average | 51°F (11°C) |
| July Average | 71°F (21°C) |
| Sunny Days | 330 days/yr |
Geography
| Elevation | 165 ft (50 m) |
| Area | 0.9 sq mi (2.2 km²) |
| Population Density | 13,355/sq mi |
| Coordinates | 37.3694°N, 121.8238°W |
| Timezone | America/Los_Angeles |
| County | Santa Clara County County |
| Nearest Airport | Norman Y Mineta San Jose International (SJC) 6 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 48.0 |
| Rating | Good |
Air Pollutants (EPA 2023)
| Ozone (O₃) | 0.0372 ppm |
| NO₂ (Nitrogen Dioxide) | 15.5 ppb |
| SO₂ (Sulfur Dioxide) | 0.16 ppb |
| CO (Carbon Monoxide) | 0.39 ppm |
| PM2.5 (Fine Particles) | 6.9 μg/m³ |
Natural Hazard Risk
| Overall Risk | Very High |
| Risk Score | 99.8 / 100 |
| Social Vulnerability | 17.2 / 100 |
| Community Resilience | 72.6 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Earthquake | Very High |
| Wildfire | Relatively Moderate |
| Flood | Very High |
| Hail | Relatively Low |
| Strong Wind | Very Low |
| Heat Wave | Relatively High |
| Winter Weather | Very Low |
| Lightning | Relatively Low |
| Drought | Relatively High |
| Cold Wave | No Rating |
| Landslide | Relatively High |
| Coastal Flood | Relatively High |
| Tsunami | Very Low |
| Volcano | Very Low |
| Avalanche | 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 | 44 km |
| 1989 | N. CALIFORNIA | Earthquake | 1.0 m | 62 | 37 km |
| 1856 | N. CALIFORNIA | Eruption + Earthquake | 0.6 m | - | 45 km |
| 1906 | N. CALIFORNIA | Eruption + Earthquake | 0.1 m | - | 70 km |
| 1865 | N. CALIFORNIA | Eruption + Earthquake | - | - | 20 km |
Source: NOAA/NCEI Historical Tsunami Database. Sorted by wave height.
Nearby Volcanoes
1 volcano within 200 km. Closest: Clear Lake (196 km).
| Name | Type | Elevation | Last Eruption | Distance |
| Clear Lake | Volcanic field | 1,439 m (4,721 ft) | Unknown | 196 km |
Source: Smithsonian Institution Global Volcanism Program (GVP). Sorted by distance.
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 51°F (11°C) | 5.8 in | Wettest |
| February | 49°F (9°C) | 4.7 in | |
| March | 50°F (10°C) | 4.4 in | |
| April | 54°F (12°C) | 2.1 in | |
| May | 59°F (15°C) | 0.5 in | |
| June | 65°F (18°C) | 0.2 in | |
| July | 71°F (21°C) | 0.1 in | Driest |
| August | 72°F (22°C) | 0.2 in | Warmest |
| September | 69°F (21°C) | 0.4 in | |
| October | 63°F (17°C) | 1.5 in | |
| November | 54°F (12°C) | 4.2 in | |
| December | 47°F (9°C) | 4.5 in | Coldest |
Alum Rock has a seasonal temperature swing of 25°F / from 47°F in December to 72°F in August. Total annual precipitation is 28.4 inches, with January being the wettest month (5.8") and July the driest (0.1").