Duncanville, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 12.9 °C (low) to 24.6 °C (high). Annual precipitation averages 1021.9 Millimeters. Duncanville 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. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.9 °C | 13.6 °C | 68.33 mm |
| February | 3.8 °C | 15.6 °C | 71.37 mm |
| March | 7.9 °C | 19.8 °C | 89.92 mm |
| April | 12.1 °C | 24.1 °C | 94.74 mm |
| May | 17.4 °C | 28.2 °C | 118.62 mm |
| June | 21.8 °C | 32.6 °C | 101.35 mm |
| July | 23.6 °C | 34.9 °C | 55.88 mm |
| August | 23.4 °C | 35.3 °C | 55.63 mm |
| September | 19.5 °C | 31.6 °C | 83.57 mm |
| October | 13.2 °C | 25.7 °C | 124.46 mm |
| November | 7.6 °C | 19.3 °C | 75.95 mm |
| December | 2.8 °C | 14.4 °C | 82.04 mm |
| Annual | 12.9 °C | 24.6 °C | 1021.86 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| 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 |