Forney, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 12.5 °C (low) to 24.4 °C (high). Annual precipitation averages 1099.8 Millimeters. Forney is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 1 - Mar. 10 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.6 °C | 13.2 °C | 73.91 mm |
| February | 3.6 °C | 15.5 °C | 79.76 mm |
| March | 7.6 °C | 19.6 °C | 98.3 mm |
| April | 11.7 °C | 23.8 °C | 107.19 mm |
| May | 17.1 °C | 27.9 °C | 127.25 mm |
| June | 21.4 °C | 32.4 °C | 102.62 mm |
| July | 23 °C | 34.7 °C | 53.59 mm |
| August | 22.8 °C | 35 °C | 62.99 mm |
| September | 19.1 °C | 31.4 °C | 81.79 mm |
| October | 12.7 °C | 25.7 °C | 132.84 mm |
| November | 7.1 °C | 19.3 °C | 86.61 mm |
| December | 2.7 °C | 14.3 °C | 92.96 mm |
| Annual | 12.5 °C | 24.4 °C | 1099.81 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 1 - Mar. 10 |
| Average Days With Frost | 30-40 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |