Alum Rock weather in December
In December, Alum Rock sees average daytime highs of 56°F and overnight lows near 40°F, with 3.9 in of rain across 8.8 wet days and about 9.5 hours of daylight. It is the 12th-warmest and 3rd-wettest month of the year here.
Day-to-day highs hold fairly steady near 56°F through the month. The sky is clear or mostly clear about 37% of the time in December, and the air most often feels dry.
Daylight stretches from about 9 h 36 min at the start of December to 9 h 30 min by month's end. Set against the rest of the year, December is Alum Rock's 9th-clearest and 5th-windiest month. For the whole year in context, see Alum Rock's year-round climate.
- Daytime high
- 56°
- 12th warmest
- Overnight low
- 40°
- 1st coldest
- Rainfall
- 3.9 in
- 8.8 wet days
- Daylight
- 9 h 24 min
- 7:20 AM – 4:47 PM
- Cloud cover
- 55%
- 9th clearest
- Wind
- 4 mph
- 5th windiest
- Solar energy
- 2.36 kWh/m²
- Travel score
- 4.0
- out of 10
Alum Rock is census-designated place in Santa Clara County, California.
- Density
- 7,068/km²
- people per km²
Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.
Temperature in December
Day-to-day highs hold fairly steady near 56°F through the month.
A typical December day in Alum Rock reaches about 56°F in the afternoon and slips back to 40°F overnight — a 16°F spread between the day's warmth and the night's chill. On most days the high lands between 49°F and 64°F. Set against its neighbours, December runs about 7°F cooler than November and on par with January.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg high (°F) | 58 | 58 | 58 | 58 | 58 | 57 | 57 | 57 | 57 | 57 | 56 | 56 | 56 | 56 | 56 | 56 | 56 | 56 | 56 | 56 | 55 | 55 | 55 | 55 | 55 | 55 | 55 | 55 | 55 | 55 | 55 |
| Avg low (°F) | 41 | 41 | 41 | 41 | 41 | 41 | 41 | 41 | 40 | 40 | 40 | 40 | 40 | 40 | 40 | 40 | 40 | 40 | 39 | 39 | 39 | 39 | 39 | 39 | 39 | 39 | 39 | 39 | 39 | 39 | 39 |
| Avg high (°F) | Avg low (°F) | |
|---|---|---|
| 1 | 58 | 41 |
| 2 | 58 | 41 |
| 3 | 58 | 41 |
| 4 | 58 | 41 |
| 5 | 58 | 41 |
| 6 | 57 | 41 |
| 7 | 57 | 41 |
| 8 | 57 | 41 |
| 9 | 57 | 40 |
| 10 | 57 | 40 |
| 11 | 56 | 40 |
| 12 | 56 | 40 |
| 13 | 56 | 40 |
| 14 | 56 | 40 |
| 15 | 56 | 40 |
| 16 | 56 | 40 |
| 17 | 56 | 40 |
| 18 | 56 | 40 |
| 19 | 56 | 39 |
| 20 | 56 | 39 |
| 21 | 55 | 39 |
| 22 | 55 | 39 |
| 23 | 55 | 39 |
| 24 | 55 | 39 |
| 25 | 55 | 39 |
| 26 | 55 | 39 |
| 27 | 55 | 39 |
| 28 | 55 | 39 |
| 29 | 55 | 39 |
| 30 | 55 | 39 |
| 31 | 55 | 39 |
Alum Rock weather by month
How December compares with the rest of the year at a glance. December is the 12th-warmest and 3rd-wettest month here — the current month is highlighted below.
| Month | High / Low (°F) | Rainfall (inches) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 56° / 40° | 4.4 | 9.1 | 9.7 | 4.1 |
| Feb | 58° / 42° | 4.4 | 9.2 | 10.6 | 4.4 |
| Mar | 61° / 44° | 3.3 | 9.2 | 11.7 | 5.4 |
| Apr | 65° / 45° | 1.6 | 5.7 | 12.9 | 6.7 |
| May | 71° / 49° | 0.8 | 3.4 | 14 | 8.1 |
| Jun | 77° / 53° | 0.2 | 0.8 | 14.5 | 9.1 |
| Jul | 82° / 57° | 0.1 | 0.2 | 14.3 | 8.8 |
| Aug | 82° / 57° | 0.0 | 0.3 | 13.4 | 8.8 |
| Sep | 80° / 56° | 0.1 | 0.6 | 12.3 | 8.9 |
| Oct | 73° / 51° | 1.0 | 2.8 | 11 | 8.6 |
| Nov | 63° / 44° | 1.9 | 5.7 | 10 | 6.2 |
| Dec | 56° / 40° | 3.9 | 8.8 | 9.5 | 4.0 |
Cloud cover in December
The sky is clear or mostly clear about 37% of the time in December.
Beyond those clear spells, partly cloudy skies cover about 13% of December, with mostly cloudy or overcast conditions the remaining 49%.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Clearer (%) | 53 | 53 | 52 | 51 | 50 | 50 | 49 | 50 | 50 | 50 | 49 | 49 | 50 | 50 | 51 | 51 | 51 | 52 | 52 | 52 | 52 | 52 | 52 | 51 | 51 | 50 | 50 | 50 | 49 | 48 | 47 |
| Cloudier (%) | 47 | 47 | 48 | 49 | 50 | 50 | 51 | 50 | 50 | 50 | 51 | 51 | 50 | 50 | 49 | 49 | 49 | 48 | 48 | 48 | 48 | 48 | 48 | 49 | 49 | 50 | 50 | 50 | 51 | 52 | 53 |
| Clearer (%) | Cloudier (%) | |
|---|---|---|
| 1 | 53 | 47 |
| 2 | 53 | 47 |
| 3 | 52 | 48 |
| 4 | 51 | 49 |
| 5 | 50 | 50 |
| 6 | 50 | 50 |
| 7 | 49 | 51 |
| 8 | 50 | 50 |
| 9 | 50 | 50 |
| 10 | 50 | 50 |
| 11 | 49 | 51 |
| 12 | 49 | 51 |
| 13 | 50 | 50 |
| 14 | 50 | 50 |
| 15 | 51 | 49 |
| 16 | 51 | 49 |
| 17 | 51 | 49 |
| 18 | 52 | 48 |
| 19 | 52 | 48 |
| 20 | 52 | 48 |
| 21 | 52 | 48 |
| 22 | 52 | 48 |
| 23 | 52 | 48 |
| 24 | 51 | 49 |
| 25 | 51 | 49 |
| 26 | 50 | 50 |
| 27 | 50 | 50 |
| 28 | 50 | 50 |
| 29 | 49 | 51 |
| 30 | 48 | 52 |
| 31 | 47 | 53 |
Chance of precipitation in December
Alum Rock gets around 3.9 in of rain over 8.8 wet days in December. The line is the day-by-day chance of measurable precipitation.
Day to day, the chance of measurable rain averages around 28% and peaks near 30% on the wettest days.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Rain chance (%) | 27 | 27 | 28 | 29 | 29 | 29 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 30 | 29 | 29 | 28 | 28 | 27 | 27 | 27 | 27 | 27 | 27 | 27 | 27 | 27 | 28 | 28 | 28 | 29 |
| Rain chance (%) | |
|---|---|
| 1 | 27 |
| 2 | 27 |
| 3 | 28 |
| 4 | 29 |
| 5 | 29 |
| 6 | 29 |
| 7 | 30 |
| 8 | 30 |
| 9 | 30 |
| 10 | 30 |
| 11 | 30 |
| 12 | 30 |
| 13 | 30 |
| 14 | 30 |
| 15 | 29 |
| 16 | 29 |
| 17 | 28 |
| 18 | 28 |
| 19 | 27 |
| 20 | 27 |
| 21 | 27 |
| 22 | 27 |
| 23 | 27 |
| 24 | 27 |
| 25 | 27 |
| 26 | 27 |
| 27 | 27 |
| 28 | 28 |
| 29 | 28 |
| 30 | 28 |
| 31 | 29 |
Humidity in December
Most of December feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
By dew point, December lands in the dry band about 99% of days. It rarely turns muggy — the humid and sticky bands barely register.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Dry (%) | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 100 | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 99 | 99 |
| Comfortable (%) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Dry (%) | Comfortable (%) | |
|---|---|---|
| 1 | 99 | 1 |
| 2 | 99 | 1 |
| 3 | 99 | 1 |
| 4 | 99 | 1 |
| 5 | 99 | 1 |
| 6 | 99 | 1 |
| 7 | 99 | 1 |
| 8 | 99 | 1 |
| 9 | 99 | 1 |
| 10 | 99 | 1 |
| 11 | 99 | 1 |
| 12 | 100 | 0 |
| 13 | 100 | 0 |
| 14 | 100 | 0 |
| 15 | 100 | 0 |
| 16 | 100 | 0 |
| 17 | 100 | 0 |
| 18 | 100 | 0 |
| 19 | 100 | 0 |
| 20 | 99 | 1 |
| 21 | 99 | 1 |
| 22 | 99 | 1 |
| 23 | 99 | 1 |
| 24 | 99 | 1 |
| 25 | 99 | 1 |
| 26 | 99 | 1 |
| 27 | 99 | 1 |
| 28 | 99 | 1 |
| 29 | 99 | 1 |
| 30 | 99 | 1 |
| 31 | 99 | 1 |
Wind in December
Winds average 4 mph in December.
Across December, daily wind ranges from about 4 mph on the calmest days to 4 mph at its breeziest. It stays fairly steady from day to day.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Wind speed (mph) | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 |
| Feels | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm | calm |
| Wind speed (mph) | Feels | |
|---|---|---|
| 1 | 4 | calm |
| 2 | 4 | calm |
| 3 | 4 | calm |
| 4 | 4 | calm |
| 5 | 4 | calm |
| 6 | 4 | calm |
| 7 | 4 | calm |
| 8 | 4 | calm |
| 9 | 4 | calm |
| 10 | 4 | calm |
| 11 | 4 | calm |
| 12 | 4 | calm |
| 13 | 4 | calm |
| 14 | 4 | calm |
| 15 | 4 | calm |
| 16 | 4 | calm |
| 17 | 4 | calm |
| 18 | 4 | calm |
| 19 | 4 | calm |
| 20 | 4 | calm |
| 21 | 4 | calm |
| 22 | 4 | calm |
| 23 | 4 | calm |
| 24 | 4 | calm |
| 25 | 4 | calm |
| 26 | 4 | calm |
| 27 | 4 | calm |
| 28 | 4 | calm |
| 29 | 4 | calm |
| 30 | 4 | calm |
| 31 | 4 | calm |
Sunrise & sunset in December
Daylight runs from about 9 h 36 min at the start of December to 9 h 30 min by month's end. The lit band spans sunrise to sunset each day.
Days shrink by about 6 minutes over December. Sunrise moves from 7:09 AM to 7:27 AM, and sunset from 4:45 PM to 4:54 PM.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight (h) | 9.6 | 9.6 | 9.6 | 9.6 | 9.5 | 9.5 | 9.5 | 9.5 | 9.5 | 9.5 | 9.5 | 9.5 | 9.5 | 9.5 | 9.4 | 9.4 | 9.4 | 9.4 | 9.4 | 9.4 | 9.4 | 9.4 | 9.4 | 9.4 | 9.4 | 9.4 | 9.4 | 9.4 | 9.4 | 9.5 | 9.5 |
| Sunrise (AM) | 7:09 | 7:10 | 7:10 | 7:11 | 7:12 | 7:13 | 7:14 | 7:15 | 7:15 | 7:16 | 7:17 | 7:18 | 7:18 | 7:19 | 7:20 | 7:20 | 7:21 | 7:22 | 7:22 | 7:23 | 7:23 | 7:24 | 7:24 | 7:25 | 7:25 | 7:25 | 7:26 | 7:26 | 7:26 | 7:26 | 7:27 |
| Sunset (PM) | 4:45 | 4:45 | 4:45 | 4:45 | 4:45 | 4:45 | 4:45 | 4:45 | 4:45 | 4:45 | 4:45 | 4:46 | 4:46 | 4:46 | 4:46 | 4:47 | 4:47 | 4:47 | 4:48 | 4:48 | 4:48 | 4:49 | 4:49 | 4:50 | 4:50 | 4:51 | 4:52 | 4:52 | 4:53 | 4:54 | 4:54 |
| Daylight (h) | Sunrise (AM) | Sunset (PM) | |
|---|---|---|---|
| 1 | 9.6 | 7:09 | 4:45 |
| 2 | 9.6 | 7:10 | 4:45 |
| 3 | 9.6 | 7:10 | 4:45 |
| 4 | 9.6 | 7:11 | 4:45 |
| 5 | 9.5 | 7:12 | 4:45 |
| 6 | 9.5 | 7:13 | 4:45 |
| 7 | 9.5 | 7:14 | 4:45 |
| 8 | 9.5 | 7:15 | 4:45 |
| 9 | 9.5 | 7:15 | 4:45 |
| 10 | 9.5 | 7:16 | 4:45 |
| 11 | 9.5 | 7:17 | 4:45 |
| 12 | 9.5 | 7:18 | 4:46 |
| 13 | 9.5 | 7:18 | 4:46 |
| 14 | 9.5 | 7:19 | 4:46 |
| 15 | 9.4 | 7:20 | 4:46 |
| 16 | 9.4 | 7:20 | 4:47 |
| 17 | 9.4 | 7:21 | 4:47 |
| 18 | 9.4 | 7:22 | 4:47 |
| 19 | 9.4 | 7:22 | 4:48 |
| 20 | 9.4 | 7:23 | 4:48 |
| 21 | 9.4 | 7:23 | 4:48 |
| 22 | 9.4 | 7:24 | 4:49 |
| 23 | 9.4 | 7:24 | 4:49 |
| 24 | 9.4 | 7:25 | 4:50 |
| 25 | 9.4 | 7:25 | 4:50 |
| 26 | 9.4 | 7:25 | 4:51 |
| 27 | 9.4 | 7:26 | 4:52 |
| 28 | 9.4 | 7:26 | 4:52 |
| 29 | 9.4 | 7:26 | 4:53 |
| 30 | 9.5 | 7:26 | 4:54 |
| 31 | 9.5 | 7:27 | 4:54 |
Solar energy in December
Average shortwave solar energy reaching the ground each day in December, about 2.36 kWh/m² — the year's lowest.
For context, solar energy here swings from a low near 2.36 kWh/m² to a high of 7.99 kWh/m² in June across the year — December's 2.36 kWh/m² sits near the bottom.
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Solar energy (kWh/m²) | 2.5 | 2.5 | 2.4 | 2.4 | 2.4 | 2.4 | 2.4 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.4 | 2.4 | 2.4 | 2.4 | 2.4 | 2.4 | 2.4 | 2.4 |
| Level | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate |
| Solar energy (kWh/m²) | Level | |
|---|---|---|
| 1 | 2.5 | Moderate |
| 2 | 2.5 | Moderate |
| 3 | 2.4 | Moderate |
| 4 | 2.4 | Moderate |
| 5 | 2.4 | Moderate |
| 6 | 2.4 | Moderate |
| 7 | 2.4 | Moderate |
| 8 | 2.3 | Moderate |
| 9 | 2.3 | Moderate |
| 10 | 2.3 | Moderate |
| 11 | 2.3 | Moderate |
| 12 | 2.3 | Moderate |
| 13 | 2.3 | Moderate |
| 14 | 2.3 | Moderate |
| 15 | 2.3 | Moderate |
| 16 | 2.3 | Moderate |
| 17 | 2.3 | Moderate |
| 18 | 2.3 | Moderate |
| 19 | 2.3 | Moderate |
| 20 | 2.3 | Moderate |
| 21 | 2.3 | Moderate |
| 22 | 2.3 | Moderate |
| 23 | 2.3 | Moderate |
| 24 | 2.4 | Moderate |
| 25 | 2.4 | Moderate |
| 26 | 2.4 | Moderate |
| 27 | 2.4 | Moderate |
| 28 | 2.4 | Moderate |
| 29 | 2.4 | Moderate |
| 30 | 2.4 | Moderate |
| 31 | 2.4 | Moderate |
Hazard calendar for Alum Rock
In December, Alum Rock sits inside its rainy season season. The full year is below, with each hazard's peak months called out.
Alum Rock's rainy season runs December–March, when most of the year's rain falls.
Is December a good time to visit Alum Rock?
Our two travel scores rate December for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).
December is a reasonable time to visit Alum Rock for sightseeing.
What to pack for Alum Rock in December
From December's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In December, Alum Rock sees daytime highs around 56°F and nights near 40°F. Worth packing: a warm layer and rain gear. About 9 days see rain.
Sea temperature near Alum Rock in December
The nearest coast averages about 55°F in December — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 30 mi away) is warmest in August at about 59°F and coldest in April near 54°F.
The water stays below 68°F all year — cool enough that most swimmers want a wetsuit.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°F) | 54 | 54 | 54 | 54 | 54 | 55 | 57 | 59 | 59 | 58 | 56 | 55 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing |
| Sea temperature (°F) | Comfort | |
|---|---|---|
| Jan | 54 | Bracing |
| Feb | 54 | Bracing |
| Mar | 54 | Bracing |
| Apr | 54 | Bracing |
| May | 54 | Bracing |
| Jun | 55 | Bracing |
| Jul | 57 | Bracing |
| Aug | 59 | Bracing |
| Sep | 59 | Bracing |
| Oct | 58 | Bracing |
| Nov | 56 | Bracing |
| Dec | 55 | Bracing |
UV index in Alum Rock in December
Clear-sky midday UV in December peaks around 2. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Alum Rock peaks around June 23 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 15 at about 2 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 3 | 4 | 5 | 7 | 8 | 10 | 10 | 10 | 6 | 5 | 2 | 2 |
| Level | Moderate | Moderate | Moderate | High | Very high | Extreme | Extreme | Very high | High | High | Moderate | Moderate |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 3 | Moderate |
| Feb | 4 | Moderate |
| Mar | 5 | Moderate |
| Apr | 7 | High |
| May | 8 | Very high |
| Jun | 10 | Extreme |
| Jul | 10 | Extreme |
| Aug | 10 | Very high |
| Sep | 6 | High |
| Oct | 5 | High |
| Nov | 2 | Moderate |
| Dec | 2 | Moderate |
Air quality in Alum Rock in December
Average fine-particle pollution (PM2.5) through the year — so you can see where December falls, not just the annual average.
Air quality in Alum Rock is worst in August — around 34 µg/m³ PM2.5 (moderate), about 4.9× the cleanest month (June, 7 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 13 | 13 | 13 | 10 | 8 | 7 | 9 | 34 | 16 | 14 | 15 | 12 |
| Level | Moderate | Moderate | Moderate | Good | Good | Good | Good | Moderate | Moderate | Moderate | Moderate | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 13 | Moderate |
| Feb | 13 | Moderate |
| Mar | 13 | Moderate |
| Apr | 10 | Good |
| May | 8 | Good |
| Jun | 7 | Good |
| Jul | 9 | Good |
| Aug | 34 | Moderate |
| Sep | 16 | Moderate |
| Oct | 14 | Moderate |
| Nov | 15 | Moderate |
| Dec | 12 | Good |
Where is Alum Rock?
Alum Rock sits at 37.4°N, 121.8°W, 151 ft above sea level, in United States. The nearest listed city is San Jose, 4.3 mi away.
Topography around Alum Rock
How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of Alum Rock.
Within 2 miles, the terrain around Alum Rock has significant variations in elevation — a maximum elevation change of 1,129 ft around an average of 240 ft above sea level; within 10 miles, large variations in elevation — a maximum elevation change of 3,921 ft; within 50 miles, very significant variations in elevation — a maximum elevation change of 4,373 ft.
The land around Alum Rock is covered by artificial surfaces (73%) within 2 miles, artificial surfaces (42%), grassland (33%) and trees (22%) within 10 miles, and grassland (29%), trees (25%) and water (25%) within 50 miles.
United States travel facts
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 100% of US
- price level, 2025
- GDP per capita
- $90,027
- 2025
- Happiness
- 6.8 / 10
- World Happiness, 2025
- Safe drinking water
- 98%
- of population, 2024
- Homicide rate
- 5.8
- per 100k, 2023
- Road deaths
- 12.7
- per 100k/yr, 2019
- Income group
- High
- World Bank
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Alum Rock (37.3661°, -121.8272°, elevation 151 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).