| 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. 11 - Dec. 20 |
| Average Last Frost Date: | Feb. 21 - Feb. 29 |
| Koppen-Geiger Climate Zone: | Csb - Warm-Summer Mediterranean Climate |
| Ecoregion: | |
| Heat Zone Days: | 1 - 7 days Over 86°F |
Annual Climate Data for ZIP Code 94559 - Napa, CA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 39 | 42 | 43 | 45 | 49 | 53 | 55 | 54 | 53 | 49 | 43 | 38 | 47 |
| Avg Max Temp (°F) | 57 | 62 | 66 | 71 | 76 | 81 | 84 | 83 | 83 | 77 | 64 | 57 | 72 |
| Avg Precip (In.) | 5.27 | 4.97 | 3.92 | 1.32 | .76 | .16 | .05 | .1 | .36 | 1.33 | 3.55 | 3.83 | 25.62 |