Fontana, California has a Hot-Summer Mediterranean Climate climate (Köppen classification: Csa). Average annual temperatures range from 11.5 °C (low) to 26 °C (high). Annual precipitation averages 374.2 Millimeters. Fontana is located in USDA Plant Hardiness Zone 10a. 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 | 6.7 °C | 19.3 °C | 80.26 mm |
| February | 7 °C | 19.5 °C | 100.08 mm |
| March | 8.3 °C | 21.4 °C | 61.47 mm |
| April | 9.7 °C | 23.8 °C | 20.07 mm |
| May | 12.1 °C | 26.3 °C | 8.38 mm |
| June | 14.3 °C | 30.2 °C | 2.29 mm |
| July | 17.2 °C | 33.9 °C | 1.27 mm |
| August | 17.8 °C | 34.8 °C | 1.27 mm |
| September | 16.6 °C | 32.9 °C | 3.56 mm |
| October | 13.1 °C | 27.9 °C | 16 mm |
| November | 9.1 °C | 23.2 °C | 22.86 mm |
| December | 6.3 °C | 18.8 °C | 56.64 mm |
| Annual | 11.5 °C | 26 °C | 374.15 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 10a : -1.1°C to 1.7°C |
| Plant Hardiness Zone - 2012 | Zone 10a : -1.1°C to 1.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Csa - Hot-Summer Mediterranean Climate |