Vacaville, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 9.2 °C (low) to 23.8 °C (high). Annual precipitation averages 638.6 Millimeters. Vacaville is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Feb. 1 - Feb. 10 through the first frost around Dec. 21 - Dec. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.7 °C | 13.8 °C | 133.6 mm |
| February | 4.8 °C | 16.2 °C | 134.37 mm |
| March | 6.4 °C | 18.8 °C | 87.38 mm |
| April | 8.1 °C | 22.2 °C | 37.34 mm |
| May | 10.8 °C | 26.4 °C | 19.56 mm |
| June | 13.6 °C | 30.8 °C | 4.32 mm |
| July | 14.9 °C | 33.7 °C | 0 mm |
| August | 14.5 °C | 33.2 °C | 0.51 mm |
| September | 13.3 °C | 31.5 °C | 1.78 mm |
| October | 10.2 °C | 26.2 °C | 25.91 mm |
| November | 6.2 °C | 18.8 °C | 58.67 mm |
| December | 3.6 °C | 13.9 °C | 135.13 mm |
| Annual | 9.2 °C | 23.8 °C | 638.57 mm |
| Average First Frost Date | Dec. 21 - Dec. 31 |
| Average Last Frost Date | Feb. 1 - Feb. 10 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9b : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9b : -3.9°C to -1.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |