Wentzville, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.5 °C (low) to 18.9 °C (high). Annual precipitation averages 1093.7 Millimeters. Wentzville 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 | -5.6 °C | 4.2 °C | 62.48 mm |
| February | -3.8 °C | 7.3 °C | 58.93 mm |
| March | 1.1 °C | 13.1 °C | 84.84 mm |
| April | 7.1 °C | 19.7 °C | 116.84 mm |
| May | 12.9 °C | 24.4 °C | 130.56 mm |
| June | 18.1 °C | 29.1 °C | 117.35 mm |
| July | 20.1 °C | 31.2 °C | 102.87 mm |
| August | 18.9 °C | 30.6 °C | 91.69 mm |
| September | 14.3 °C | 26.8 °C | 88.39 mm |
| October | 7.7 °C | 20.4 °C | 85.6 mm |
| November | 1.8 °C | 12.9 °C | 86.87 mm |
| December | -3.1 °C | 6.6 °C | 67.31 mm |
| Annual | 7.5 °C | 18.9 °C | 1093.73 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |