Tomales, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 7.9 °C (low) to 18.5 °C (high). Annual precipitation averages 902 Millimeters. Tomales is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Jan. 21 - Jan. 31 through the first frost around Jan. 1 - Jan. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 4.9 °C | 13.8 °C | 172.97 mm |
| February | 5.8 °C | 14.7 °C | 178.56 mm |
| March | 6.2 °C | 15.7 °C | 120.4 mm |
| April | 6.8 °C | 17.1 °C | 59.44 mm |
| May | 8.3 °C | 19.1 °C | 33.53 mm |
| June | 9.7 °C | 21.3 °C | 8.89 mm |
| July | 10.7 °C | 22.2 °C | 1.02 mm |
| August | 11 °C | 22.9 °C | 2.79 mm |
| September | 10.3 °C | 22.8 °C | 3.81 mm |
| October | 8.9 °C | 21.3 °C | 42.42 mm |
| November | 7 °C | 17.3 °C | 95.76 mm |
| December | 5.1 °C | 13.6 °C | 182.37 mm |
| Annual | 7.9 °C | 18.5 °C | 901.96 mm |
| Average First Frost Date | Jan. 1 - Jan. 10 |
| Average Last Frost Date | Jan. 21 - Jan. 31 |
| 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 |