Washington, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 43.5 °F (low) to 69.8 °F (high). Annual precipitation averages 58.9 Inches. Washington is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 33.5 °F | 51.8 °F | 10.31 in. |
| February | 34.3 °F | 55.3 °F | 9.69 in. |
| March | 36.4 °F | 59.8 °F | 8.94 in. |
| April | 39.2 °F | 64.2 °F | 4.95 in. |
| May | 45.4 °F | 73.0 °F | 3.06 in. |
| June | 51.0 °F | 82.7 °F | 0.88 in. |
| July | 57.5 °F | 90.7 °F | 0.06 in. |
| August | 56.8 °F | 90.4 °F | 0.14 in. |
| September | 52.4 °F | 85.2 °F | 0.53 in. |
| October | 44.7 °F | 73.9 °F | 2.9 in. |
| November | 37.3 °F | 59.6 °F | 6.08 in. |
| December | 33.7 °F | 50.7 °F | 11.38 in. |
| Annual | 43.5 °F | 69.8 °F | 58.92 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 9a : 20°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |