Mills River, North Carolina has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 6.6 °C (low) to 19.4 °C (high). Annual precipitation averages 1308.4 Millimeters. Mills River is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.4 °C | 8.5 °C | 119.38 mm |
| February | -2.1 °C | 10.7 °C | 85.6 mm |
| March | 1.2 °C | 14.6 °C | 108.2 mm |
| April | 5.6 °C | 19.9 °C | 110.74 mm |
| May | 10.6 °C | 23.8 °C | 103.89 mm |
| June | 15.2 °C | 27.2 °C | 114.3 mm |
| July | 17.2 °C | 28.8 °C | 128.02 mm |
| August | 16.6 °C | 28.1 °C | 131.32 mm |
| September | 13.2 °C | 25.4 °C | 100.58 mm |
| October | 6.5 °C | 20.3 °C | 91.44 mm |
| November | 0.8 °C | 14.7 °C | 99.31 mm |
| December | -1.8 °C | 10.2 °C | 115.57 mm |
| Annual | 6.6 °C | 19.4 °C | 1308.35 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| 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 |