Modesto, California has a Cold Semi-Arid Climate climate (Köppen classification: BSk). Average annual temperatures range from 9.3 °C (low) to 23.6 °C (high). Annual precipitation averages 322.3 Millimeters. Modesto 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 | 3.7 °C | 12.9 °C | 71.63 mm |
| February | 5 °C | 16.1 °C | 52.58 mm |
| March | 6.6 °C | 19.1 °C | 52.58 mm |
| April | 8.2 °C | 22.2 °C | 25.65 mm |
| May | 11.1 °C | 26.8 °C | 15.75 mm |
| June | 13.7 °C | 31.1 °C | 2.54 mm |
| July | 15.6 °C | 33.9 °C | 0 mm |
| August | 15.1 °C | 33.2 °C | 0.25 mm |
| September | 13.5 °C | 30.9 °C | 2.29 mm |
| October | 10 °C | 25.7 °C | 15.75 mm |
| November | 5.8 °C | 18.4 °C | 29.72 mm |
| December | 3.3 °C | 13.2 °C | 53.59 mm |
| Annual | 9.3 °C | 23.6 °C | 322.33 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 | BSk - Cold Semi-Arid Climate |