Alleghany, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 42.2 °F (low) to 64.7 °F (high). Annual precipitation averages 58.2 Inches. Alleghany is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 32.5 °F | 48.9 °F | 8.64 in. |
| February | 32.1 °F | 50.2 °F | 9.04 in. |
| March | 33.6 °F | 53.7 °F | 9.45 in. |
| April | 36.4 °F | 59.1 °F | 5.52 in. |
| May | 43.4 °F | 67.6 °F | 3.65 in. |
| June | 50.1 °F | 77.0 °F | 1.33 in. |
| July | 57.3 °F | 85.0 °F | 0.09 in. |
| August | 57.0 °F | 84.7 °F | 0.17 in. |
| September | 51.5 °F | 79.9 °F | 0.51 in. |
| October | 44.1 °F | 68.9 °F | 2.77 in. |
| November | 36.6 °F | 54.8 °F | 5.82 in. |
| December | 31.9 °F | 47.1 °F | 11.24 in. |
| Annual | 42.2 °F | 64.7 °F | 58.23 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 8b : 15°F to 20°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 |