Belmont, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 49.3 °F (low) to 68.2 °F (high). Annual precipitation averages 20 Inches. Belmont is located in USDA Plant Hardiness Zone 10a. The growing season typically runs from the last frost around Jan. 21 - Jan. 31 through the first frost around Dec. 21 - Dec. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 42.5 °F | 58.5 °F | 3.89 in. |
| February | 44.2 °F | 61.0 °F | 3.98 in. |
| March | 46.0 °F | 63.9 °F | 2.91 in. |
| April | 47.4 °F | 66.2 °F | 1.5 in. |
| May | 50.6 °F | 69.4 °F | 0.61 in. |
| June | 53.2 °F | 74.0 °F | 0.16 in. |
| July | 55.5 °F | 76.4 °F | 0.02 in. |
| August | 55.8 °F | 76.6 °F | 0.03 in. |
| September | 55.0 °F | 76.8 °F | 0.08 in. |
| October | 52.1 °F | 72.9 °F | 0.84 in. |
| November | 46.5 °F | 64.3 °F | 1.85 in. |
| December | 42.3 °F | 58.5 °F | 4.12 in. |
| Annual | 49.3 °F | 68.2 °F | 19.99 in. |
| Average First Frost Date | Dec. 21 - Dec. 31 |
| Average Last Frost Date | Jan. 21 - Jan. 31 |
| Average Days With Frost | Frost Rare |
| Plant Hardiness Zone | Zone 10a : 30°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 10a : 30°F to 25°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |