San Carlos, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 9.7 °C (low) to 20.3 °C (high). Annual precipitation averages 483.4 Millimeters. 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 | 5.9 °C | 14.6 °C | 97.03 mm |
| February | 6.8 °C | 16.1 °C | 96.77 mm |
| March | 7.8 °C | 17.6 °C | 71.37 mm |
| April | 8.7 °C | 19.3 °C | 34.54 mm |
| May | 10.6 °C | 21.2 °C | 12.45 mm |
| June | 12.1 °C | 23.8 °C | 3.81 mm |
| July | 13.4 °C | 25 °C | 0.51 mm |
| August | 13.6 °C | 25.1 °C | 0.51 mm |
| September | 12.9 °C | 25.1 °C | 2.03 mm |
| October | 11.1 °C | 22.8 °C | 20.32 mm |
| November | 8.1 °C | 17.8 °C | 44.7 mm |
| December | 5.8 °C | 14.7 °C | 99.31 mm |
| Annual | 9.7 °C | 20.3 °C | 483.35 mm |
| 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 : -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 |