Vernon, Illinois has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 45.1 °F (low) to 65 °F (high). Annual precipitation averages 44.1 Inches. Vernon is located in USDA Plant Hardiness Zone 6b. 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 | 21.9 °F | 38.2 °F | 3.01 in. |
| February | 25.3 °F | 43.2 °F | 2.48 in. |
| March | 34.2 °F | 53.7 °F | 3.51 in. |
| April | 44.5 °F | 65.8 °F | 4.58 in. |
| May | 55.3 °F | 75.3 °F | 5.03 in. |
| June | 64.1 °F | 84.3 °F | 4.63 in. |
| July | 67.2 °F | 87.4 °F | 4.02 in. |
| August | 64.8 °F | 86.3 °F | 3.51 in. |
| September | 56.6 °F | 80.1 °F | 3.41 in. |
| October | 45.1 °F | 68.4 °F | 3.39 in. |
| November | 35.1 °F | 54.1 °F | 3.65 in. |
| December | 26.6 °F | 42.6 °F | 2.83 in. |
| Annual | 45.1 °F | 65 °F | 44.05 in. |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |