South San Francisco, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 10.3 °C (low) to 18.5 °C (high). Annual precipitation averages 584.2 Millimeters. South San Francisco is located in USDA Plant Hardiness Zone 10b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 7.1 °C | 14.3 °C | 113.54 mm |
| February | 7.9 °C | 15.7 °C | 119.13 mm |
| March | 8.7 °C | 16.8 °C | 83.82 mm |
| April | 9.3 °C | 17.5 °C | 43.18 mm |
| May | 10.8 °C | 18.6 °C | 17.53 mm |
| June | 12 °C | 20.1 °C | 4.57 mm |
| July | 12.9 °C | 20.8 °C | 2.03 mm |
| August | 13.4 °C | 21.2 °C | 1.78 mm |
| September | 13.3 °C | 22.8 °C | 2.03 mm |
| October | 11.9 °C | 21.8 °C | 23.37 mm |
| November | 9.2 °C | 17.6 °C | 55.37 mm |
| December | 7.2 °C | 14.6 °C | 117.86 mm |
| Annual | 10.3 °C | 18.5 °C | 584.21 mm |
| Average First Frost Date | No Frost |
| Average Last Frost Date | |
| Average Days With Frost | Frost Free |
| Plant Hardiness Zone | Zone 10b : 1.7°C to 4.4°C |
| Plant Hardiness Zone - 2012 | Zone 10b : 1.7°C to 4.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |