San Martin, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 8 °C (low) to 22.7 °C (high). Annual precipitation averages 515.6 Millimeters. San Martin is located in USDA Plant Hardiness Zone 9b. 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 | 4.1 °C | 15.6 °C | 109.98 mm |
| February | 4.9 °C | 16.7 °C | 111.51 mm |
| March | 5.9 °C | 18.8 °C | 73.91 mm |
| April | 6.9 °C | 20.6 °C | 35.05 mm |
| May | 8.9 °C | 23.7 °C | 14.48 mm |
| June | 10.8 °C | 28.2 °C | 2.79 mm |
| July | 12.2 °C | 29.4 °C | 0 mm |
| August | 12.3 °C | 30 °C | 0.51 mm |
| September | 11.5 °C | 29 °C | 1.27 mm |
| October | 9.1 °C | 25.2 °C | 23.37 mm |
| November | 5.8 °C | 19.6 °C | 39.88 mm |
| December | 3.4 °C | 15.5 °C | 102.87 mm |
| Annual | 8 °C | 22.7 °C | 515.62 mm |
| Average First Frost Date | Dec. 11 - Dec. 20 |
| Average Last Frost Date | Jan. 21 - Jan. 31 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9b : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9b : -3.9°C to -1.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |