Dennis, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 12 °C (low) to 25.5 °C (high). Annual precipitation averages 849.4 Millimeters. Dennis is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 0.5 °C | 14.5 °C | 49.02 mm |
| February | 2.8 °C | 16.6 °C | 60.2 mm |
| March | 7.1 °C | 20.9 °C | 78.49 mm |
| April | 11.3 °C | 25.3 °C | 73.66 mm |
| May | 16.8 °C | 29.1 °C | 97.79 mm |
| June | 21.3 °C | 33.4 °C | 88.65 mm |
| July | 23.1 °C | 35.9 °C | 41.4 mm |
| August | 22.7 °C | 36.1 °C | 64.26 mm |
| September | 18.5 °C | 32.1 °C | 79.5 mm |
| October | 12.3 °C | 26.4 °C | 96.52 mm |
| November | 6.4 °C | 19.9 °C | 64.01 mm |
| December | 1.6 °C | 15.3 °C | 55.88 mm |
| Annual | 12 °C | 25.5 °C | 849.38 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 50-75 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 |