Greenbrier, Tennessee has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.6 °C (low) to 20.1 °C (high). Annual precipitation averages 1355.1 Millimeters. Greenbrier is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.1 °C | 7.1 °C | 103.38 mm |
| February | -1.3 °C | 9.7 °C | 115.82 mm |
| March | 2.9 °C | 14.7 °C | 123.44 mm |
| April | 8.1 °C | 20.5 °C | 130.56 mm |
| May | 13.6 °C | 25.1 °C | 140.97 mm |
| June | 17.9 °C | 29.1 °C | 109.47 mm |
| July | 19.7 °C | 30.8 °C | 117.09 mm |
| August | 18.9 °C | 31.1 °C | 95.5 mm |
| September | 15.2 °C | 27.6 °C | 102.87 mm |
| October | 8.6 °C | 21.4 °C | 96.77 mm |
| November | 3 °C | 14.6 °C | 95.5 mm |
| December | -0.7 °C | 9.1 °C | 123.7 mm |
| Annual | 8.6 °C | 20.1 °C | 1355.07 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°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 |