Onyx, California has a Hot Desert Climate climate (Köppen classification: BWh). Average annual temperatures range from 47.4 °F (low) to 75.9 °F (high). Annual precipitation averages 10.5 Inches. Onyx is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 34.3 °F | 58.1 °F | 2.66 in. |
| February | 35.8 °F | 60.2 °F | 2.57 in. |
| March | 39.1 °F | 65.3 °F | 1.26 in. |
| April | 43.4 °F | 70.7 °F | 0.6 in. |
| May | 51.1 °F | 79.5 °F | 0.23 in. |
| June | 59.0 °F | 89.8 °F | 0.11 in. |
| July | 64.5 °F | 97.2 °F | 0.15 in. |
| August | 63.1 °F | 97.1 °F | 0.22 in. |
| September | 58.3 °F | 90.8 °F | 0.13 in. |
| October | 48.1 °F | 78.9 °F | 0.51 in. |
| November | 39.0 °F | 66.3 °F | 0.71 in. |
| December | 33.5 °F | 57.0 °F | 1.37 in. |
| Annual | 47.4 °F | 75.9 °F | 10.52 in. |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 50-75 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 | BWh - Hot Desert Climate |