Antioch, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 9.8 °C (low) to 22.4 °C (high). Annual precipitation averages 366.5 Millimeters. Antioch 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. 1 - Dec. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 4.3 °C | 13.2 °C | 74.68 mm |
| February | 5.7 °C | 15.9 °C | 71.88 mm |
| March | 7.4 °C | 18.6 °C | 49.02 mm |
| April | 9.1 °C | 21.1 °C | 26.92 mm |
| May | 11.6 °C | 24.6 °C | 12.7 mm |
| June | 13.8 °C | 28.3 °C | 3.05 mm |
| July | 14.8 °C | 31.1 °C | 0 mm |
| August | 14.9 °C | 30.4 °C | 1.02 mm |
| September | 14 °C | 29.1 °C | 1.78 mm |
| October | 11.2 °C | 24.8 °C | 16.26 mm |
| November | 6.8 °C | 18.2 °C | 37.59 mm |
| December | 4.2 °C | 13.3 °C | 71.63 mm |
| Annual | 9.8 °C | 22.4 °C | 366.53 mm |
| Average First Frost Date | Dec. 1 - Dec. 10 |
| 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 | Csb - Warm-Summer Mediterranean Climate |