Mount Vernon, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.4 °C (low) to 15.9 °C (high). Annual precipitation averages 1061.2 Millimeters. Mount Vernon is located in USDA Plant Hardiness Zone 6a. 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 | -7.7 °C | 1.5 °C | 84.33 mm |
| February | -6.8 °C | 3.2 °C | 61.47 mm |
| March | -2.3 °C | 8.8 °C | 85.85 mm |
| April | 3.4 °C | 16.3 °C | 98.04 mm |
| May | 9.3 °C | 21.8 °C | 110.74 mm |
| June | 14.4 °C | 26.4 °C | 119.38 mm |
| July | 16.2 °C | 28.3 °C | 105.66 mm |
| August | 15.2 °C | 27.7 °C | 88.39 mm |
| September | 11.1 °C | 24.3 °C | 84.07 mm |
| October | 4.7 °C | 17.7 °C | 71.37 mm |
| November | -0.3 °C | 10.3 °C | 74.68 mm |
| December | -4.5 °C | 4.1 °C | 77.22 mm |
| Annual | 4.4 °C | 15.9 °C | 1061.2 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |