| 2023 Hardiness Zone: | Zone 9a: 20°F to 25°F Zone 9b: 25°F to 30°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: | Jan. 21 - Jan. 31 |
| Koppen-Geiger Climate Zone: | Csb - Warm-Summer Mediterranean Climate |
| Ecoregion: | |
| Heat Zone Days: | 61 - 90 days Over 86°F |
Annual Climate Data for ZIP Code 94533 - Fairfield, CA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 38 | 41 | 44 | 47 | 51 | 55 | 57 | 57 | 55 | 50 | 43 | 37 | 48 |
| Avg Max Temp (°F) | 55 | 61 | 66 | 72 | 78 | 85 | 89 | 89 | 86 | 78 | 65 | 55 | 73 |
| Avg Precip (In.) | 4.93 | 4.42 | 3.49 | 1.13 | .63 | .15 | .03 | .05 | .3 | 1.2 | 2.94 | 3.51 | 22.8 |