Helena, Alabama has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.9 °C (low) to 23.9 °C (high). Annual precipitation averages 1448.8 Millimeters. Helena is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Mar. 21 - Mar. 31 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 0.8 °C | 13.1 °C | 135.13 mm |
| February | 2.4 °C | 15.6 °C | 142.49 mm |
| March | 6 °C | 19.9 °C | 137.41 mm |
| April | 9.9 °C | 24.2 °C | 132.59 mm |
| May | 14.9 °C | 28.2 °C | 108.71 mm |
| June | 19.2 °C | 31.4 °C | 121.16 mm |
| July | 21.1 °C | 33.2 °C | 116.59 mm |
| August | 20.7 °C | 32.8 °C | 115.06 mm |
| September | 17.5 °C | 30.4 °C | 107.19 mm |
| October | 10.9 °C | 24.8 °C | 83.31 mm |
| November | 4.9 °C | 18.8 °C | 116.33 mm |
| December | 2.1 °C | 14.2 °C | 132.84 mm |
| Annual | 10.9 °C | 23.9 °C | 1448.81 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Mar. 21 - Mar. 31 |
| Average Days With Frost | 50-75 Days |
| Plant Hardiness Zone | Zone 8a : -12.2°C to -9.4°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |