Castaic, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 51.1 °F (low) to 78 °F (high). Annual precipitation averages 16.2 Inches. Castaic is located in USDA Plant Hardiness Zone 10a. The growing season typically runs from the last frost around Feb. 1 - Feb. 10 through the first frost around Dec. 21 - Dec. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 44.1 °F | 65.1 °F | 3.87 in. |
| February | 43.6 °F | 65.9 °F | 4.35 in. |
| March | 45.4 °F | 69.6 °F | 2.5 in. |
| April | 47.6 °F | 74.1 °F | 0.74 in. |
| May | 51.4 °F | 79.1 °F | 0.5 in. |
| June | 55.3 °F | 85.7 °F | 0.04 in. |
| July | 60.3 °F | 92.7 °F | 0.07 in. |
| August | 60.7 °F | 94.1 °F | 0.02 in. |
| September | 58.7 °F | 90.8 °F | 0.08 in. |
| October | 53.9 °F | 82.1 °F | 0.53 in. |
| November | 48.0 °F | 72.6 °F | 0.78 in. |
| December | 43.6 °F | 64.6 °F | 2.75 in. |
| Annual | 51.1 °F | 78 °F | 16.23 in. |
| Average First Frost Date | Dec. 21 - Dec. 31 |
| Average Last Frost Date | Feb. 1 - Feb. 10 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 10a : 30°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 9b : 25°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |