| 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: | Dec. 21 - Dec. 31 |
| Average Last Frost Date: | Feb. 11 - Feb. 20 |
| Koppen-Geiger Climate Zone: | Csb - Warm-Summer Mediterranean Climate |
| Ecoregion: | |
| Heat Zone Days: | 8 - 14 days Over 86°F |
Annual Climate Data for ZIP Code 94552 - Castro Valley, CA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 40 | 43 | 44 | 46 | 49 | 53 | 55 | 55 | 55 | 51 | 44 | 39 | 48 |
| Avg Max Temp (°F) | 55 | 60 | 62 | 67 | 71 | 76 | 79 | 79 | 78 | 73 | 63 | 56 | 68 |
| Avg Precip (In.) | 4.71 | 4.25 | 3.41 | 1.55 | .74 | .13 | .06 | .08 | .32 | 1.34 | 2.97 | 3.27 | 22.82 |