Karns, Tennessee has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 48.3 °F (low) to 69.6 °F (high). Annual precipitation averages 56.4 Inches. Karns 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 | 28.8 °F | 47.3 °F | 5.09 in. |
| February | 31.7 °F | 51.9 °F | 5.2 in. |
| March | 38.2 °F | 61.0 °F | 5.21 in. |
| April | 46.8 °F | 70.9 °F | 5.24 in. |
| May | 56.2 °F | 78.6 °F | 4.31 in. |
| June | 64.1 °F | 85.1 °F | 4.73 in. |
| July | 68.1 °F | 88.0 °F | 5.96 in. |
| August | 66.9 °F | 87.5 °F | 3.49 in. |
| September | 60.8 °F | 82.7 °F | 4.09 in. |
| October | 48.6 °F | 71.8 °F | 3.3 in. |
| November | 37.5 °F | 59.8 °F | 4.1 in. |
| December | 32.2 °F | 50.4 °F | 5.67 in. |
| Annual | 48.3 °F | 69.6 °F | 56.39 in. |
| 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 : 5°F to 10°F |
| Plant Hardiness Zone - 2012 | Zone 7a : 0°F to 5°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |