South San Francisco, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 50.6 °F (low) to 65.3 °F (high). Annual precipitation averages 23 Inches. South San Francisco is located in USDA Plant Hardiness Zone 10b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 44.8 °F | 57.8 °F | 4.47 in. |
| February | 46.3 °F | 60.2 °F | 4.69 in. |
| March | 47.7 °F | 62.3 °F | 3.3 in. |
| April | 48.8 °F | 63.5 °F | 1.7 in. |
| May | 51.5 °F | 65.5 °F | 0.69 in. |
| June | 53.6 °F | 68.2 °F | 0.18 in. |
| July | 55.3 °F | 69.4 °F | 0.08 in. |
| August | 56.2 °F | 70.2 °F | 0.07 in. |
| September | 55.9 °F | 73.0 °F | 0.08 in. |
| October | 53.4 °F | 71.2 °F | 0.92 in. |
| November | 48.6 °F | 63.7 °F | 2.18 in. |
| December | 44.9 °F | 58.2 °F | 4.64 in. |
| Annual | 50.6 °F | 65.3 °F | 23 in. |
| Average First Frost Date | No Frost |
| Average Last Frost Date | |
| Average Days With Frost | Frost Free |
| Plant Hardiness Zone | Zone 10b : 35°F to 30°F |
| Plant Hardiness Zone - 2012 | Zone 10b : 35°F to 30°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |