Willis, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 14 °C (low) to 25.8 °C (high). Annual precipitation averages 1272.8 Millimeters. Willis is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Feb. 11 - Feb. 20 through the first frost around Nov. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 4.3 °C | 16.2 °C | 107.19 mm |
| February | 6.3 °C | 18.2 °C | 83.57 mm |
| March | 9.8 °C | 22 °C | 95.25 mm |
| April | 13.5 °C | 25.5 °C | 91.69 mm |
| May | 18.2 °C | 29.4 °C | 126.75 mm |
| June | 21.7 °C | 32.6 °C | 119.38 mm |
| July | 22.9 °C | 34.1 °C | 84.07 mm |
| August | 22.7 °C | 34.7 °C | 105.16 mm |
| September | 19.8 °C | 31.7 °C | 103.38 mm |
| October | 14.4 °C | 27.1 °C | 130.81 mm |
| November | 9.1 °C | 21.3 °C | 118.36 mm |
| December | 5.4 °C | 16.9 °C | 107.19 mm |
| Annual | 14 °C | 25.8 °C | 1272.8 mm |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| Average Last Frost Date | Feb. 11 - Feb. 20 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |