Unionville, Tennessee has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.3 °C (low) to 21.2 °C (high). Annual precipitation averages 1416.8 Millimeters. Unionville is located in USDA Plant Hardiness Zone 7b. 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 | -2.4 °C | 8.8 °C | 119.63 mm |
| February | -0.8 °C | 11.3 °C | 127.25 mm |
| March | 2.7 °C | 16.2 °C | 140.21 mm |
| April | 7.4 °C | 21.5 °C | 128.27 mm |
| May | 13 °C | 25.8 °C | 121.16 mm |
| June | 17.4 °C | 29.8 °C | 122.68 mm |
| July | 19.7 °C | 31.4 °C | 118.87 mm |
| August | 18.7 °C | 31.5 °C | 95.5 mm |
| September | 14.8 °C | 28.6 °C | 108.46 mm |
| October | 8 °C | 22.6 °C | 87.63 mm |
| November | 2.3 °C | 15.8 °C | 99.57 mm |
| December | -0.7 °C | 10.5 °C | 147.57 mm |
| Annual | 8.3 °C | 21.2 °C | 1416.8 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 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |