San Rafael, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 8.9 °C (low) to 20.8 °C (high). Annual precipitation averages 1007.6 Millimeters. San Rafael is located in USDA Plant Hardiness Zone 9b.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 5.6 °C | 13.5 °C | 204.72 mm |
| February | 6.4 °C | 15.7 °C | 207.77 mm |
| March | 7.1 °C | 17.4 °C | 134.87 mm |
| April | 8 °C | 19.8 °C | 60.71 mm |
| May | 9.6 °C | 22.5 °C | 28.96 mm |
| June | 11.1 °C | 25.4 °C | 6.35 mm |
| July | 12 °C | 26.7 °C | 0 mm |
| August | 12.3 °C | 26.9 °C | 1.27 mm |
| September | 11.8 °C | 26.7 °C | 2.29 mm |
| October | 10.1 °C | 23.7 °C | 44.2 mm |
| November | 7.6 °C | 17.8 °C | 99.57 mm |
| December | 5.5 °C | 13.7 °C | 216.92 mm |
| Annual | 8.9 °C | 20.8 °C | 1007.63 mm |
| Average First Frost Date | Frost Rare |
| Average Last Frost Date | |
| Average Days With Frost | Frost Rare |
| Plant Hardiness Zone | Zone 9b : -3.9°C to -1.1°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 |