Round Mountain, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 45.5 °F (low) to 71.8 °F (high). Annual precipitation averages 63.6 Inches. Round Mountain is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 35.1 °F | 53.2 °F | 10.87 in. |
| February | 35.8 °F | 56.0 °F | 9.28 in. |
| March | 37.9 °F | 60.5 °F | 9.02 in. |
| April | 41.1 °F | 66.4 °F | 5.94 in. |
| May | 47.7 °F | 76.0 °F | 3.72 in. |
| June | 54.4 °F | 86.1 °F | 1.38 in. |
| July | 60.2 °F | 95.3 °F | 0.1 in. |
| August | 58.8 °F | 94.3 °F | 0.25 in. |
| September | 54.3 °F | 87.8 °F | 0.68 in. |
| October | 46.6 °F | 74.2 °F | 3.45 in. |
| November | 39.1 °F | 59.8 °F | 6.75 in. |
| December | 34.7 °F | 51.6 °F | 12.17 in. |
| Annual | 45.5 °F | 71.8 °F | 63.61 in. |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 9a : 20°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 9a : 20°F to 25°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |