Terrell, 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 1070.9 Millimeters. Terrell 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 | 1.6 °C | 13.2 °C | 73.15 mm |
| February | 3.6 °C | 15.5 °C | 79.5 mm |
| March | 7.6 °C | 19.7 °C | 98.81 mm |
| April | 11.7 °C | 23.9 °C | 90.68 mm |
| May | 17 °C | 28.1 °C | 125.22 mm |
| June | 21.4 °C | 32.4 °C | 98.04 mm |
| July | 23.1 °C | 34.6 °C | 50.8 mm |
| August | 22.8 °C | 35 °C | 66.55 mm |
| September | 19 °C | 31.4 °C | 74.42 mm |
| October | 12.8 °C | 25.7 °C | 129.79 mm |
| November | 7.1 °C | 19.2 °C | 89.15 mm |
| December | 2.6 °C | 14.3 °C | 94.74 mm |
| Annual | 12.5 °C | 24.4 °C | 1070.85 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 40-50 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 |