Hayfork, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 36.4 °F (low) to 69.8 °F (high). Annual precipitation averages 36.4 Inches. Hayfork is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 28.8 °F | 50.0 °F | 6.84 in. |
| February | 28.9 °F | 54.7 °F | 5.45 in. |
| March | 31.0 °F | 59.2 °F | 5.24 in. |
| April | 33.5 °F | 64.7 °F | 2.33 in. |
| May | 38.9 °F | 74.0 °F | 1.6 in. |
| June | 43.2 °F | 83.0 °F | 0.66 in. |
| July | 48.8 °F | 93.0 °F | 0.24 in. |
| August | 47.3 °F | 92.5 °F | 0.16 in. |
| September | 41.7 °F | 86.8 °F | 0.34 in. |
| October | 34.8 °F | 73.2 °F | 1.91 in. |
| November | 31.6 °F | 57.8 °F | 4.07 in. |
| December | 28.4 °F | 48.7 °F | 7.53 in. |
| Annual | 36.4 °F | 69.8 °F | 36.37 in. |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8a : 10°F to 15°F |
| Plant Hardiness Zone - 2012 | Zone 8a : 10°F to 15°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |