Mount Vernon, Indiana has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 47 °F (low) to 66.8 °F (high). Annual precipitation averages 46.5 Inches. Mount Vernon is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 25.1 °F | 41.2 °F | 3.52 in. |
| February | 27.8 °F | 46.1 °F | 3.09 in. |
| March | 36.0 °F | 55.8 °F | 4.21 in. |
| April | 46.2 °F | 67.5 °F | 5.07 in. |
| May | 57.0 °F | 76.8 °F | 5.09 in. |
| June | 65.6 °F | 85.3 °F | 4.46 in. |
| July | 68.5 °F | 87.9 °F | 3.96 in. |
| August | 66.1 °F | 86.9 °F | 2.93 in. |
| September | 58.6 °F | 82.0 °F | 3.3 in. |
| October | 47.3 °F | 70.2 °F | 3.32 in. |
| November | 36.6 °F | 56.4 °F | 3.81 in. |
| December | 29.1 °F | 45.6 °F | 3.69 in. |
| Annual | 47 °F | 66.8 °F | 46.45 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |