San Bruno, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 50.5 °F (low) to 65.6 °F (high). Annual precipitation averages 21.7 Inches. San Bruno is located in USDA Plant Hardiness Zone 10a.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 44.4 °F | 58.0 °F | 4.32 in. |
| February | 45.9 °F | 60.3 °F | 4.42 in. |
| March | 47.5 °F | 62.5 °F | 3.17 in. |
| April | 48.7 °F | 63.8 °F | 1.62 in. |
| May | 51.7 °F | 65.9 °F | 0.6 in. |
| June | 53.7 °F | 68.7 °F | 0.16 in. |
| July | 55.6 °F | 70.0 °F | 0.06 in. |
| August | 56.4 °F | 70.8 °F | 0.05 in. |
| September | 55.9 °F | 73.5 °F | 0.08 in. |
| October | 53.3 °F | 71.4 °F | 0.87 in. |
| November | 48.2 °F | 63.5 °F | 2.03 in. |
| December | 44.4 °F | 58.2 °F | 4.3 in. |
| Annual | 50.5 °F | 65.6 °F | 21.68 in. |
| Average First Frost Date | No Frost |
| Average Last Frost Date | |
| Average Days With Frost | Frost Free |
| 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 |