Thornton, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 13.1 °C (low) to 25.5 °C (high). Annual precipitation averages 1036.6 Millimeters. Thornton is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.7 °C | 14.9 °C | 83.82 mm |
| February | 4.8 °C | 17.2 °C | 74.93 mm |
| March | 8.4 °C | 20.9 °C | 94.49 mm |
| April | 12.5 °C | 25.1 °C | 88.14 mm |
| May | 17.4 °C | 28.8 °C | 113.03 mm |
| June | 21.4 °C | 32.9 °C | 92.96 mm |
| July | 22.9 °C | 35.1 °C | 52.58 mm |
| August | 22.7 °C | 35.6 °C | 70.87 mm |
| September | 19.2 °C | 32.3 °C | 81.28 mm |
| October | 13.4 °C | 26.8 °C | 107.7 mm |
| November | 8.1 °C | 20.4 °C | 82.55 mm |
| December | 3.8 °C | 15.8 °C | 94.23 mm |
| Annual | 13.1 °C | 25.5 °C | 1036.58 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°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 |