| 2023 Hardiness Zone: | Zone 9a: 20°F to 25°F 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: | Jan. 21 - Jan. 31 |
| Koppen-Geiger Climate Zone: | Csb - Warm-Summer Mediterranean Climate |
| Ecoregion: | |
| Heat Zone Days: | 46 - 60 days Over 86°F |
Annual Climate Data for ZIP Code 94534 - Fairfield, CA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 38 | 41 | 44 | 46 | 50 | 54 | 56 | 56 | 55 | 50 | 44 | 38 | 48 |
| Avg Max Temp (°F) | 55 | 61 | 65 | 71 | 78 | 85 | 89 | 89 | 86 | 78 | 64 | 55 | 73 |
| Avg Precip (In.) | 5.04 | 4.52 | 3.52 | 1.22 | .64 | .15 | .04 | .07 | .3 | 1.29 | 2.87 | 3.57 | 23.22 |