Folsom, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 9.8 °C (low) to 23.5 °C (high). Annual precipitation averages 628.9 Millimeters. 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 | 4.1 °C | 13.1 °C | 118.36 mm |
| February | 5.3 °C | 15.8 °C | 113.28 mm |
| March | 7 °C | 18.6 °C | 96.01 mm |
| April | 8.3 °C | 21.8 °C | 48.77 mm |
| May | 11.2 °C | 26.3 °C | 34.29 mm |
| June | 14.3 °C | 30.8 °C | 6.1 mm |
| July | 16.3 °C | 34.2 °C | 0.25 mm |
| August | 15.9 °C | 34 °C | 0.51 mm |
| September | 14.3 °C | 31.2 °C | 3.81 mm |
| October | 10.7 °C | 25.4 °C | 32.26 mm |
| November | 6.4 °C | 18 °C | 60.2 mm |
| December | 3.8 °C | 13.3 °C | 115.06 mm |
| Annual | 9.8 °C | 23.5 °C | 628.9 mm |
| 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 : -3.9°C to -1.1°C |
| Plant Hardiness Zone - 2012 | Zone 9b : -3.9°C to -1.1°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |