Belmont, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 9.6 °C (low) to 20.1 °C (high). Annual precipitation averages 507.7 Millimeters. 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 | 5.8 °C | 14.7 °C | 98.81 mm |
| February | 6.8 °C | 16.1 °C | 101.09 mm |
| March | 7.8 °C | 17.7 °C | 73.91 mm |
| April | 8.6 °C | 19 °C | 38.1 mm |
| May | 10.3 °C | 20.8 °C | 15.49 mm |
| June | 11.8 °C | 23.3 °C | 4.06 mm |
| July | 13.1 °C | 24.7 °C | 0.51 mm |
| August | 13.2 °C | 24.8 °C | 0.76 mm |
| September | 12.8 °C | 24.9 °C | 2.03 mm |
| October | 11.2 °C | 22.7 °C | 21.34 mm |
| November | 8.1 °C | 17.9 °C | 46.99 mm |
| December | 5.7 °C | 14.7 °C | 104.65 mm |
| Annual | 9.6 °C | 20.1 °C | 507.74 mm |
| 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 : -1.1°C to 1.7°C |
| Plant Hardiness Zone - 2012 | Zone 10a : -1.1°C to 1.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |