Charleston, Tennessee has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.7 °C (low) to 21.4 °C (high). Annual precipitation averages 1471.2 Millimeters. Charleston 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 | -1.8 °C | 9.3 °C | 137.41 mm |
| February | -0.3 °C | 11.8 °C | 122.43 mm |
| March | 3.1 °C | 16.6 °C | 145.03 mm |
| April | 7.7 °C | 21.9 °C | 126.24 mm |
| May | 13.2 °C | 26.2 °C | 111.25 mm |
| June | 17.7 °C | 29.9 °C | 123.95 mm |
| July | 19.9 °C | 31.6 °C | 139.95 mm |
| August | 19.2 °C | 31.3 °C | 97.79 mm |
| September | 15.6 °C | 28.5 °C | 120.65 mm |
| October | 8.5 °C | 22.7 °C | 82.3 mm |
| November | 2.2 °C | 16.1 °C | 119.13 mm |
| December | -0.3 °C | 10.9 °C | 145.03 mm |
| Annual | 8.7 °C | 21.4 °C | 1471.16 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 | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |