Dennis, Mississippi has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 9.7 °C (low) to 22.1 °C (high). Annual precipitation averages 1526 Millimeters. Dennis is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -1.3 °C | 10.2 °C | 134.62 mm |
| February | 0.5 °C | 12.9 °C | 138.43 mm |
| March | 4.4 °C | 17.7 °C | 142.24 mm |
| April | 9.2 °C | 22.8 °C | 138.43 mm |
| May | 14.3 °C | 26.9 °C | 148.08 mm |
| June | 18.8 °C | 30.3 °C | 113.54 mm |
| July | 20.4 °C | 31.9 °C | 122.17 mm |
| August | 20.1 °C | 32.1 °C | 112.52 mm |
| September | 16.1 °C | 29.1 °C | 104.9 mm |
| October | 9.5 °C | 23.3 °C | 98.04 mm |
| November | 3.6 °C | 16.8 °C | 112.78 mm |
| December | 0.5 °C | 11.7 °C | 160.27 mm |
| Annual | 9.7 °C | 22.1 °C | 1526.02 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |