| 2023 Hardiness Zone: | Zone 9b: 25°F to 30°F Zone 10a: 30°F to 35°F |
| 2012 Hardiness Zone: | Zone 9b: 25°F to 30°F Zone 10a: 30°F to 35°F |
| 1990 Hardiness Zone: | Zone 9b: 25F to 30F |
| Average First Frost Date: | Jan. 11 - Jan. 20 |
| Average Last Frost Date: | Feb. 1 - Feb. 10 |
| Koppen-Geiger Climate Zone: | Csb - Warm-Summer Mediterranean Climate |
| Ecoregion: | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 94546 - Castro Valley, CA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 41 | 44 | 45 | 47 | 50 | 53 | 55 | 56 | 55 | 52 | 45 | 41 | 49 |
| Avg Max Temp (°F) | 56 | 60 | 62 | 67 | 70 | 74 | 77 | 77 | 77 | 73 | 63 | 57 | 68 |
| Avg Precip (In.) | 4.77 | 4.28 | 3.74 | 1.55 | .66 | .13 | .06 | .09 | .31 | 1.37 | 3.07 | 3.37 | 23.41 |