| 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: | Jan. 21 - Jan. 31 |
| Average Last Frost Date: | Jan. 21 - Jan. 31 |
| Koppen-Geiger Climate Zone: | Csb - Warm-Summer Mediterranean Climate |
| Ecoregion: | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 94587 - Union City, CA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 40 | 43 | 44 | 47 | 50 | 54 | 56 | 57 | 56 | 51 | 45 | 40 | 49 |
| Avg Max Temp (°F) | 57 | 61 | 64 | 68 | 72 | 77 | 79 | 80 | 79 | 74 | 64 | 57 | 69 |
| Avg Precip (In.) | 3.45 | 3.22 | 2.84 | 1.1 | .51 | .11 | .04 | .07 | .24 | .99 | 2.21 | 2.38 | 17.17 |