UTC Offset
UTC-07:00
Castro Valley, United States Snapshot 2026
Where is Castro Valley?
Castro Valley, United States
- Continent
- Americas
- Country
- United States
- City
- Castro Valley
- Population
- 61.4K
- Elevation
- 50 m
- Coordinates
- 37.69°, -122.09°
Castro Valley is a city in United States with a population of approximately 61.4K. Average temperatures range from 7°C (44°F) in January to 27°C (81°F) in August. The best time to visit is May, June, July, August, September.
Time in Castro Valley right now
Open full time & time zone page 11:41 41
Monday, June 15, 2026
IANA time zone
America/Los_Angeles
Daylight saving
DST in effect
PST / PDT
Next DST change
November 1
backward -1h
Live weather in Castro Valley
Daylight in Castro Valley today
View full sunrise & sunset page Sunrise
Sunset
Day length
14h 45m
Climate normals for Castro Valley
Long-term monthly averages based on historical data.
January
Fair 
February
Fair March
Good April
Good May best
Excellent June best
Excellent July best
Excellent August best
Excellent September best
Excellent October
Excellent November
Good December
Fair | Month | Temp | Feels Like | Rain | Sun | Humidity | UV | Status | Details |
|---|---|---|---|---|---|---|---|---|
| January | 15°C / 7°C | 13°C / 5°C | 10days (102 mm) Wet | 6.8h Fair | 82% Humid | 3 Moderate | Fair | View Details |
| February | 16°C / 7°C | 14°C / 5°C | 7days (80 mm) Good | 8.4h Good | 75% Muggy | 3.8 Moderate | Fair | View Details |
| March | 17°C / 8°C | 15°C / 6°C | 11days (87 mm) Wet | 9.3h Good | 76% Humid | 5.6 High | Good | View Details |
| April | 20°C / 9°C | 19°C / 8°C | 4days (26 mm) Good | 11h Excellent | 73% Muggy | 6.9 High | Good | View Details |
| May best | 23°C / 11°C | 22°C / 10°C | 2days (14 mm) Excellent | 12.6h Excellent | 69% Muggy | 7.9 Very High | Excellent | View Details |
| June best | 26°C / 13°C | 26°C / 12°C | 0days (1 mm) Excellent | 13.5h Excellent | 65% Muggy | 8.2 Very High | Excellent | View Details |
| July best | 27°C / 14°C | 27°C / 14°C | 0days (0 mm) Excellent | 13.4h Excellent | 67% Muggy | 8.2 Very High | Excellent | View Details |
| August best | 27°C / 15°C | 28°C / 15°C | 0days (0 mm) Excellent | 12.5h Excellent | 69% Muggy | 7.7 Very High | Excellent | View Details |
| September best | 27°C / 15°C | 27°C / 15°C | 1days (3 mm) Excellent | 11.3h Excellent | 68% Muggy | 6.4 High | Excellent | View Details |
| October | 24°C / 13°C | 23°C / 13°C | 2days (22 mm) Excellent | 9.7h Good | 66% Muggy | 5 Moderate | Excellent | View Details |
| November | 18°C / 10°C | 17°C / 8°C | 6days (44 mm) Good | 8h Good | 74% Muggy | 3.4 Moderate | Good | View Details |
| December | 15°C / 7°C | 13°C / 5°C | 9days (86 mm) Wet | 6.6h Fair | 81% Humid | 2.8 Moderate | Fair | View Details |
Monthly Temperatures
HighLow
Line chart showing monthly temperatures. Jan: 15°C / 7°C . Feb: 16°C / 7°C . Mar: 17°C / 8°C . Apr: 20°C / 9°C . May: 23°C / 11°C . Jun: 26°C / 13°C . Jul: 27°C / 14°C . Aug: 27°C / 15°C . Sep: 27°C / 15°C . Oct: 24°C / 13°C . Nov: 18°C / 10°C . Dec: 15°C / 7°C .
Monthly Rainfall
Rainfall
Bar chart showing monthly rainfall. Jan: 102 mm. Feb: 80 mm. Mar: 87 mm. Apr: 26 mm. May: 14 mm. Jun: 1 mm. Jul: 0 mm. Aug: 0 mm. Sep: 3 mm. Oct: 22 mm. Nov: 44 mm. Dec: 86 mm.
Monthly Humidity
Humidity
Line chart showing monthly humidity. Jan: 82%. Feb: 75%. Mar: 76%. Apr: 73%. May: 69%. Jun: 65%. Jul: 67%. Aug: 69%. Sep: 68%. Oct: 66%. Nov: 74%. Dec: 81%.
Monthly Wind Speed
Wind SpeedGusts
Bar chart showing monthly wind speed. Jan: 13 km/h . Feb: 15 km/h . Mar: 16 km/h . Apr: 16 km/h . May: 17 km/h . Jun: 17 km/h . Jul: 16 km/h . Aug: 15 km/h . Sep: 14 km/h . Oct: 12 km/h . Nov: 11 km/h . Dec: 12 km/h .
Sea Temperature
Sea Temperatureswim
Line chart showing monthly sea temperature. Jan: 12°C . Feb: 12°C . Mar: 14°C . Apr: 17°C . May: 19°C . Jun: 21°C . Jul: 22°C . Aug: 22°C . Sep: 22°C . Oct: 20°C . Nov: 16°C . Dec: 13°C .
UV Index
UV Index
Bar chart showing monthly UV index. Jan: UV 3. Feb: UV 4. Mar: UV 6. Apr: UV 7. May: UV 8. Jun: UV 8. Jul: UV 8. Aug: UV 8. Sep: UV 6. Oct: UV 5. Nov: UV 3. Dec: UV 3.
Frequently Asked Questions
Castro Valley has a population of approximately 61.4K.
The best months to visit Castro Valley are May, June, July, August, September, when temperatures are pleasant and rainfall is lower.
Castro Valley receives approximately 465mm of rainfall annually across 52 rainy days.
Castro Valley is located in United States, in the Americas region.
Castro Valley sits at an elevation of 50 m (164 ft) above sea level.