Alleghany, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 5.7 °C (low) to 18.2 °C (high). Annual precipitation averages 1479.1 Millimeters. 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 | 0.3 °C | 9.4 °C | 219.46 mm |
| February | 0.1 °C | 10.1 °C | 229.62 mm |
| March | 0.9 °C | 12.1 °C | 240.03 mm |
| April | 2.4 °C | 15.1 °C | 140.21 mm |
| May | 6.3 °C | 19.8 °C | 92.71 mm |
| June | 10.1 °C | 25 °C | 33.78 mm |
| July | 14.1 °C | 29.4 °C | 2.29 mm |
| August | 13.9 °C | 29.3 °C | 4.32 mm |
| September | 10.8 °C | 26.6 °C | 12.95 mm |
| October | 6.7 °C | 20.5 °C | 70.36 mm |
| November | 2.6 °C | 12.7 °C | 147.83 mm |
| December | -0.1 °C | 8.4 °C | 285.5 mm |
| Annual | 5.7 °C | 18.2 °C | 1479.06 mm |
| 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 : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |