Mount Vernon, Alabama has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 12.6 °C (low) to 24.8 °C (high). Annual precipitation averages 1659.6 Millimeters. Mount Vernon is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Feb. 21 - Feb. 29 through the first frost around Nov. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.9 °C | 15.3 °C | 154.94 mm |
| February | 3.8 °C | 17.4 °C | 128.27 mm |
| March | 6.9 °C | 21.3 °C | 140.21 mm |
| April | 10.6 °C | 25 °C | 127.25 mm |
| May | 17.5 °C | 29 °C | 125.98 mm |
| June | 19.4 °C | 31.9 °C | 170.43 mm |
| July | 22.8 °C | 32.2 °C | 175.01 mm |
| August | 22.6 °C | 32.1 °C | 155.96 mm |
| September | 20.2 °C | 30.1 °C | 129.54 mm |
| October | 13.9 °C | 26.2 °C | 93.47 mm |
| November | 7.9 °C | 20.7 °C | 115.82 mm |
| December | 3.1 °C | 16.6 °C | 142.75 mm |
| Annual | 12.6 °C | 24.8 °C | 1659.63 mm |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| Average Last Frost Date | Feb. 21 - Feb. 29 |
| Average Days With Frost | 20-30 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 |