Mount Vernon, Kentucky has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7 °C (low) to 18.8 °C (high). Annual precipitation averages 1261.6 Millimeters. Mount Vernon is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.2 °C | 6.2 °C | 105.66 mm |
| February | -2.7 °C | 8.2 °C | 88.39 mm |
| March | 1.1 °C | 13.6 °C | 117.35 mm |
| April | 6.3 °C | 19.7 °C | 115.57 mm |
| May | 11.7 °C | 23.7 °C | 123.7 mm |
| June | 16.2 °C | 27.6 °C | 131.06 mm |
| July | 18.3 °C | 29.1 °C | 120.65 mm |
| August | 17.4 °C | 29 °C | 86.36 mm |
| September | 13.5 °C | 26.1 °C | 86.36 mm |
| October | 6.9 °C | 20.3 °C | 84.33 mm |
| November | 1.5 °C | 13.6 °C | 87.38 mm |
| December | -1.8 °C | 8.1 °C | 114.81 mm |
| Annual | 7 °C | 18.8 °C | 1261.62 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |