Mountain City, Tennessee has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 5.1 °C (low) to 18.5 °C (high). Annual precipitation averages 1193.5 Millimeters. Mountain City is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5 °C | 6.8 °C | 92.96 mm |
| February | -3.7 °C | 8.8 °C | 90.42 mm |
| March | -0.3 °C | 13.3 °C | 109.47 mm |
| April | 4.1 °C | 18.9 °C | 108.71 mm |
| May | 9.1 °C | 23.1 °C | 128.78 mm |
| June | 13.8 °C | 26.6 °C | 119.38 mm |
| July | 15.6 °C | 28.3 °C | 128.52 mm |
| August | 15.1 °C | 27.9 °C | 109.22 mm |
| September | 11.6 °C | 25.1 °C | 70.36 mm |
| October | 4.7 °C | 19.9 °C | 65.02 mm |
| November | -0.6 °C | 13.9 °C | 70.36 mm |
| December | -3.2 °C | 8.8 °C | 100.33 mm |
| Annual | 5.1 °C | 18.5 °C | 1193.53 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |