Vandalia, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43.6 °F (low) to 63.8 °F (high). Annual precipitation averages 40.8 Inches. Vandalia 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 | 19.2 °F | 36.6 °F | 2.14 in. |
| February | 22.4 °F | 41.5 °F | 2.2 in. |
| March | 31.9 °F | 52.8 °F | 3.11 in. |
| April | 42.9 °F | 64.6 °F | 4.13 in. |
| May | 53.6 °F | 74.2 °F | 4.97 in. |
| June | 63.0 °F | 82.9 °F | 4.83 in. |
| July | 66.7 °F | 86.8 °F | 4.61 in. |
| August | 64.7 °F | 85.7 °F | 3.38 in. |
| September | 56.1 °F | 79.1 °F | 3.5 in. |
| October | 44.5 °F | 67.0 °F | 3.12 in. |
| November | 33.5 °F | 53.2 °F | 2.59 in. |
| December | 24.3 °F | 40.9 °F | 2.2 in. |
| Annual | 43.6 °F | 63.8 °F | 40.78 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 |