McMullen, Alabama has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 11.3 °C (low) to 23.8 °C (high). Annual precipitation averages 1389.6 Millimeters. McMullen 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 Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 0.9 °C | 12.6 °C | 136.65 mm |
| February | 2.7 °C | 15.1 °C | 138.18 mm |
| March | 6.5 °C | 19.8 °C | 133.6 mm |
| April | 10.8 °C | 24.1 °C | 137.92 mm |
| May | 15.8 °C | 28.1 °C | 97.54 mm |
| June | 20.1 °C | 31.6 °C | 112.01 mm |
| July | 21.8 °C | 33.1 °C | 117.09 mm |
| August | 21.2 °C | 32.9 °C | 105.66 mm |
| September | 17.8 °C | 30.5 °C | 91.69 mm |
| October | 11.1 °C | 25.1 °C | 90.68 mm |
| November | 5.1 °C | 18.6 °C | 105.16 mm |
| December | 2.2 °C | 13.9 °C | 123.44 mm |
| Annual | 11.3 °C | 23.8 °C | 1389.62 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| 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 |