| 2023 Hardiness Zone: | Zone 9b: 25°F to 30°F |
| 2012 Hardiness Zone: | Zone 9b: 25°F to 30°F |
| 1990 Hardiness Zone: | Zone 9b: 25F to 30F |
| Average First Frost Date: | Dec. 11 - Dec. 20 |
| Average Last Frost Date: | Mar. 1 - Mar. 10 |
| Koppen-Geiger Climate Zone: | Csb - Warm-Summer Mediterranean Climate |
| Ecoregion: | |
| Heat Zone Days: | 15 - 30 days Over 86°F |
Annual Climate Data for ZIP Code 94528 - Diablo, CA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 37 | 40 | 41 | 43 | 48 | 52 | 56 | 56 | 54 | 48 | 42 | 37 | 46 |
| Avg Max Temp (°F) | 55 | 59 | 62 | 67 | 73 | 80 | 85 | 85 | 82 | 75 | 62 | 55 | 70 |
| Avg Precip (In.) | 4.43 | 3.98 | 2.89 | 1.38 | .84 | .1 | .05 | .08 | .24 | 1.19 | 2.27 | 2.98 | 20.43 |