Round Mountain, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 7.5 °C (low) to 22.1 °C (high). Annual precipitation averages 1615.7 Millimeters. 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 | 1.7 °C | 11.8 °C | 276.1 mm |
| February | 2.1 °C | 13.3 °C | 235.71 mm |
| March | 3.3 °C | 15.8 °C | 229.11 mm |
| April | 5.1 °C | 19.1 °C | 150.88 mm |
| May | 8.7 °C | 24.4 °C | 94.49 mm |
| June | 12.4 °C | 30.1 °C | 35.05 mm |
| July | 15.7 °C | 35.2 °C | 2.54 mm |
| August | 14.9 °C | 34.6 °C | 6.35 mm |
| September | 12.4 °C | 31 °C | 17.27 mm |
| October | 8.1 °C | 23.4 °C | 87.63 mm |
| November | 3.9 °C | 15.4 °C | 171.45 mm |
| December | 1.5 °C | 10.9 °C | 309.12 mm |
| Annual | 7.5 °C | 22.1 °C | 1615.7 mm |
| 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 : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 9a : -6.7°C to -3.9°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |