Average annual temperature is 13.6 °C
Absolute maximum temperature: 34.3 °C
Absolute minimum temperature: 0.3 °C
Number of sunny days: 235 days
Number of rainy days: 130 days
Look at detailed online map of Castro Valley
* Weather data for Castro Valley United States is based on climate observations for 2026 year
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Absolute maximum temperature (°C) | 17.5 | 17.0 | 18.4 | 24.1 | 22.7 | 25.0 | 29.7 | 30.8 | 26.0 | 34.3 | 25.0 | 19.4 |
| Average daytime temperature (°C) | 13.9 | 13.4 | 13.2 | 15.8 | 17.1 | 19.3 | 23.0 | 24.6 | 22.2 | 23.9 | 18.8 | 15.8 |
| Average temperature (°C) | 9.9 | 8.4 | 9.5 | 11.6 | 13.4 | 15.1 | 17.1 | 18.7 | 17.3 | 17.3 | 13.1 | 11.2 |
| Average night temperature (°C) | 7.1 | 4.6 | 6.9 | 8.4 | 11.1 | 12.5 | 13.2 | 15.0 | 14.2 | 12.7 | 8.8 | 8.0 |
| Absolute minimum temperature (°C) | 0.3 | 1.2 | 2.1 | 3.7 | 8.4 | 11.1 | 11.8 | 13.1 | 12.0 | 4.9 | 3.0 | 2.2 |
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Daylight maximum duration (h) | 10.0 | 11.0 | 12.0 | 13.0 | 14.0 | 14.0 | 14.0 | 14.0 | 13.0 | 11.0 | 10.0 | 9.0 |
| Daylight mean duration (h) | 9.9 | 10.8 | 12.0 | 13.2 | 14.2 | 14.7 | 14.5 | 13.6 | 12.4 | 11.2 | 10.2 | 9.6 |
| Daylight minimum duration (h) | 9.0 | 10.0 | 11.0 | 12.0 | 13.0 | 14.0 | 14.0 | 13.0 | 11.0 | 10.0 | 9.0 | 9.0 |
| Sunshine mean duration (h) | 6.0 | 7.7 | 7.8 | 11.0 | 10.3 | 12.2 | 12.4 | 11.7 | 10.3 | 9.5 | 8.3 | 6.1 |
| Precipitation (mm) | 319 | 139 | 287 | 6 | 45 | 6 | 0 | 3 | 6 | 12 | 74 | 126 |
| Sunny days | 11 | 13 | 10 | 22 | 16 | 24 | 27 | 24 | 25 | 26 | 21 | 16 |
| Rainy days | 20 | 15 | 21 | 8 | 15 | 6 | 4 | 7 | 5 | 5 | 9 | 15 |
| Snow days | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
The best time to visit Castro Valley during the most sunny months:
The largest precipitation sum in Castro Valley is at