Summertown, Tennessee has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.6 °C (low) to 20.9 °C (high). Annual precipitation averages 1497.3 Millimeters. Summertown is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.3 °C | 9.1 °C | 122.68 mm |
| February | -0.7 °C | 11.5 °C | 132.59 mm |
| March | 3.1 °C | 16.3 °C | 141.73 mm |
| April | 7.9 °C | 21.7 °C | 138.68 mm |
| May | 12.9 °C | 25.4 °C | 139.19 mm |
| June | 17.3 °C | 29.1 °C | 124.97 mm |
| July | 19.3 °C | 30.8 °C | 127 mm |
| August | 18.8 °C | 30.7 °C | 108.97 mm |
| September | 15.1 °C | 27.9 °C | 111 mm |
| October | 8.6 °C | 22.2 °C | 96.52 mm |
| November | 3.2 °C | 15.7 °C | 104.65 mm |
| December | -0.3 °C | 10.3 °C | 149.35 mm |
| Annual | 8.6 °C | 20.9 °C | 1497.33 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |