San Carlos, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 49.5 °F (low) to 68.5 °F (high). Annual precipitation averages 19 Inches. San Carlos 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. 11 - Dec. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 42.6 °F | 58.2 °F | 3.82 in. |
| February | 44.3 °F | 60.9 °F | 3.81 in. |
| March | 46.1 °F | 63.7 °F | 2.81 in. |
| April | 47.6 °F | 66.8 °F | 1.36 in. |
| May | 51.0 °F | 70.2 °F | 0.49 in. |
| June | 53.7 °F | 74.8 °F | 0.15 in. |
| July | 56.1 °F | 77.0 °F | 0.02 in. |
| August | 56.4 °F | 77.2 °F | 0.02 in. |
| September | 55.3 °F | 77.2 °F | 0.08 in. |
| October | 52.0 °F | 73.1 °F | 0.8 in. |
| November | 46.5 °F | 64.1 °F | 1.76 in. |
| December | 42.4 °F | 58.4 °F | 3.91 in. |
| Annual | 49.5 °F | 68.5 °F | 19.03 in. |
| Average First Frost Date | Dec. 11 - Dec. 20 |
| 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 |