Julian, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 46.6 °F (low) to 69.1 °F (high). Annual precipitation averages 26.4 Inches. Julian is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 37.7 °F | 55.3 °F | 5.18 in. |
| February | 37.2 °F | 54.8 °F | 5.8 in. |
| March | 39.2 °F | 59.3 °F | 4.21 in. |
| April | 40.7 °F | 63.2 °F | 1.92 in. |
| May | 45.6 °F | 69.9 °F | 0.85 in. |
| June | 53.5 °F | 80.0 °F | 0.13 in. |
| July | 60.8 °F | 86.6 °F | 0.3 in. |
| August | 61.0 °F | 87.6 °F | 0.47 in. |
| September | 56.0 °F | 82.7 °F | 0.48 in. |
| October | 48.1 °F | 72.4 °F | 1.09 in. |
| November | 42.0 °F | 62.5 °F | 2.16 in. |
| December | 36.9 °F | 54.4 °F | 3.85 in. |
| Annual | 46.6 °F | 69.1 °F | 26.44 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |