Denison, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 11.5 °C (low) to 23.2 °C (high). Annual precipitation averages 1063 Millimeters. Denison is located in USDA Plant Hardiness Zone 8a. 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 | 0 °C | 11.6 °C | 56.9 mm |
| February | 1.9 °C | 13.9 °C | 65.53 mm |
| March | 6.2 °C | 18.4 °C | 94.49 mm |
| April | 10.4 °C | 22.7 °C | 92.71 mm |
| May | 15.8 °C | 26.7 °C | 137.41 mm |
| June | 20.6 °C | 31.4 °C | 107.7 mm |
| July | 22.8 °C | 34.2 °C | 76.45 mm |
| August | 22.3 °C | 34.3 °C | 67.82 mm |
| September | 18.2 °C | 30.3 °C | 89.66 mm |
| October | 11.9 °C | 24.6 °C | 106.43 mm |
| November | 6.1 °C | 18.1 °C | 84.33 mm |
| December | 1.3 °C | 12.7 °C | 83.57 mm |
| Annual | 11.5 °C | 23.2 °C | 1063 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 8a : -12.2°C to -9.4°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 |