San Martin, California has a Warm-Summer Mediterranean Climate climate (Köppen classification: Csb). Average annual temperatures range from 46.4 °F (low) to 72.8 °F (high). Annual precipitation averages 20.3 Inches. 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 | 39.3 °F | 60.1 °F | 4.33 in. |
| February | 40.9 °F | 62.1 °F | 4.39 in. |
| March | 42.7 °F | 65.8 °F | 2.91 in. |
| April | 44.5 °F | 69.1 °F | 1.38 in. |
| May | 48.0 °F | 74.6 °F | 0.57 in. |
| June | 51.4 °F | 82.7 °F | 0.11 in. |
| July | 54.0 °F | 84.9 °F | 0.0 in. |
| August | 54.2 °F | 86.0 °F | 0.02 in. |
| September | 52.7 °F | 84.2 °F | 0.05 in. |
| October | 48.3 °F | 77.4 °F | 0.92 in. |
| November | 42.5 °F | 67.3 °F | 1.57 in. |
| December | 38.2 °F | 59.9 °F | 4.05 in. |
| Annual | 46.4 °F | 72.8 °F | 20.3 in. |
| 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 : 25°F to 20°F |
| Plant Hardiness Zone - 2012 | Zone 9b : 25°F to 20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csb - Warm-Summer Mediterranean Climate |