Cosby, Tennessee has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.9 °C (low) to 20.5 °C (high). Annual precipitation averages 1371.6 Millimeters. Cosby is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -2.2 °C | 8.8 °C | 109.47 mm |
| February | -0.8 °C | 11.2 °C | 103.38 mm |
| March | 2.6 °C | 15.9 °C | 118.62 mm |
| April | 7 °C | 21.2 °C | 116.84 mm |
| May | 12 °C | 25.2 °C | 125.48 mm |
| June | 16.3 °C | 28.8 °C | 141.48 mm |
| July | 18.3 °C | 30.3 °C | 150.11 mm |
| August | 17.8 °C | 29.9 °C | 125.98 mm |
| September | 14.4 °C | 27.2 °C | 90.42 mm |
| October | 7.8 °C | 21.7 °C | 72.14 mm |
| November | 2.2 °C | 15.6 °C | 95 mm |
| December | -0.5 °C | 10.5 °C | 122.68 mm |
| Annual | 7.9 °C | 20.5 °C | 1371.6 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 100-125 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 | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |