Heflin, Alabama has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 9.6 °C (low) to 22.2 °C (high). Annual precipitation averages 1451.6 Millimeters. Heflin is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -0.4 °C | 11.6 °C | 137.92 mm |
| February | 1.1 °C | 13.8 °C | 149.61 mm |
| March | 4.4 °C | 18.3 °C | 141.99 mm |
| April | 8.4 °C | 22.7 °C | 117.86 mm |
| May | 13.7 °C | 26.3 °C | 121.92 mm |
| June | 18 °C | 29.7 °C | 121.92 mm |
| July | 20 °C | 31.2 °C | 125.48 mm |
| August | 19.6 °C | 30.9 °C | 105.92 mm |
| September | 16.2 °C | 28.4 °C | 88.39 mm |
| October | 9.6 °C | 23.2 °C | 87.63 mm |
| November | 3.7 °C | 17.4 °C | 121.16 mm |
| December | 1 °C | 13 °C | 131.83 mm |
| Annual | 9.6 °C | 22.2 °C | 1451.63 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 7b : -15°C to -12.2°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |