Cohasset, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 46.4 °F (low) to 69.3 °F (high). Annual precipitation averages 56.6 Inches. Cohasset is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Jan. 21 - Jan. 31 through the first frost around Jan. 11 - Jan. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 36.0 °F | 52.9 °F | 10.96 in. |
| February | 36.7 °F | 54.6 °F | 9.32 in. |
| March | 38.8 °F | 58.4 °F | 8.01 in. |
| April | 41.2 °F | 63.9 °F | 4.64 in. |
| May | 47.7 °F | 72.4 °F | 2.85 in. |
| June | 54.8 °F | 82.2 °F | 1.01 in. |
| July | 60.8 °F | 90.4 °F | 0.06 in. |
| August | 59.8 °F | 89.7 °F | 0.16 in. |
| September | 56.5 °F | 84.7 °F | 0.43 in. |
| October | 48.8 °F | 72.8 °F | 2.85 in. |
| November | 40.3 °F | 58.6 °F | 5.47 in. |
| December | 35.3 °F | 51.1 °F | 10.86 in. |
| Annual | 46.4 °F | 69.3 °F | 56.62 in. |
| Average First Frost Date | Jan. 11 - Jan. 20 |
| Average Last Frost Date | Jan. 21 - Jan. 31 |
| Average Days With Frost | 10-20 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 | Csa - Hot-Summer Mediterranean Climate |