Helenwood, Tennessee has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 6.9 °C (low) to 19.5 °C (high). Annual precipitation averages 1482.9 Millimeters. Helenwood is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.7 °C | 7.2 °C | 121.41 mm |
| February | -2.3 °C | 9.6 °C | 131.32 mm |
| March | 1.2 °C | 14.3 °C | 145.8 mm |
| April | 6 °C | 20.3 °C | 134.37 mm |
| May | 11.4 °C | 24.6 °C | 123.44 mm |
| June | 15.6 °C | 28.1 °C | 130.05 mm |
| July | 17.9 °C | 29.7 °C | 150.11 mm |
| August | 17.2 °C | 29.4 °C | 110.24 mm |
| September | 13.4 °C | 26.6 °C | 102.36 mm |
| October | 6.6 °C | 20.9 °C | 83.82 mm |
| November | 1 °C | 14.3 °C | 101.85 mm |
| December | -1.7 °C | 9.2 °C | 148.08 mm |
| Annual | 6.9 °C | 19.5 °C | 1482.85 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |