Folsom, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 49.6 °F (low) to 74.4 °F (high). Annual precipitation averages 24.8 Inches. Folsom is located in USDA Plant Hardiness Zone 9b. The growing season typically runs from the last frost around Feb. 1 - Feb. 10 through the first frost around Dec. 11 - Dec. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 39.4 °F | 55.6 °F | 4.66 in. |
| February | 41.5 °F | 60.4 °F | 4.46 in. |
| March | 44.6 °F | 65.4 °F | 3.78 in. |
| April | 46.9 °F | 71.3 °F | 1.92 in. |
| May | 52.2 °F | 79.3 °F | 1.35 in. |
| June | 57.8 °F | 87.5 °F | 0.24 in. |
| July | 61.3 °F | 93.5 °F | 0.01 in. |
| August | 60.6 °F | 93.2 °F | 0.02 in. |
| September | 57.7 °F | 88.1 °F | 0.15 in. |
| October | 51.2 °F | 77.7 °F | 1.27 in. |
| November | 43.5 °F | 64.4 °F | 2.37 in. |
| December | 38.9 °F | 55.9 °F | 4.53 in. |
| Annual | 49.6 °F | 74.4 °F | 24.76 in. |
| Average First Frost Date | Dec. 11 - Dec. 20 |
| Average Last Frost Date | Feb. 1 - Feb. 10 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |