Graball, Tennessee has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 9.1 °C (low) to 19.9 °C (high). Annual precipitation averages 1370.3 Millimeters. Graball 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 Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.6 °C | 6.9 °C | 108.2 mm |
| February | -0.7 °C | 9.6 °C | 117.86 mm |
| March | 3.6 °C | 14.7 °C | 125.98 mm |
| April | 8.6 °C | 20.4 °C | 126.24 mm |
| May | 14.1 °C | 24.8 °C | 141.99 mm |
| June | 18.2 °C | 28.9 °C | 115.06 mm |
| July | 20 °C | 30.7 °C | 121.67 mm |
| August | 19.3 °C | 30.4 °C | 97.54 mm |
| September | 15.6 °C | 27.3 °C | 97.79 mm |
| October | 9.2 °C | 21.3 °C | 93.98 mm |
| November | 3.6 °C | 14.3 °C | 98.55 mm |
| December | -0.1 °C | 8.9 °C | 125.48 mm |
| Annual | 9.1 °C | 19.9 °C | 1370.34 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| 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 | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |