Unionville, Missouri has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.4 °C (low) to 16.1 °C (high). Annual precipitation averages 1055.3 Millimeters. Unionville is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.1 °C | 0.1 °C | 33.02 mm |
| February | -7.9 °C | 2.9 °C | 43.94 mm |
| March | -2.2 °C | 9.9 °C | 65.02 mm |
| April | 3.9 °C | 16.7 °C | 103.12 mm |
| May | 10.2 °C | 22.1 °C | 137.92 mm |
| June | 15.7 °C | 27.3 °C | 150.11 mm |
| July | 18.2 °C | 29.7 °C | 123.95 mm |
| August | 16.7 °C | 28.9 °C | 115.06 mm |
| September | 11.9 °C | 24.9 °C | 104.14 mm |
| October | 5.2 °C | 17.8 °C | 76.45 mm |
| November | -1.4 °C | 9.8 °C | 59.18 mm |
| December | -6.9 °C | 2.9 °C | 43.43 mm |
| Annual | 4.4 °C | 16.1 °C | 1055.34 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°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 |