Grand Bay, Alabama has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 15.2 °C (low) to 25 °C (high). Annual precipitation averages 1728.7 Millimeters. Grand Bay is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Frost Rare through the first frost around Jan. 11 - Jan. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 5.6 °C | 16.3 °C | 141.99 mm |
| February | 7 °C | 18.1 °C | 116.84 mm |
| March | 10.7 °C | 21.6 °C | 136.14 mm |
| April | 14.7 °C | 24.7 °C | 139.95 mm |
| May | 19.3 °C | 28.4 °C | 138.43 mm |
| June | 22.6 °C | 31.2 °C | 170.43 mm |
| July | 23.4 °C | 32.3 °C | 213.87 mm |
| August | 23.5 °C | 32.3 °C | 182.88 mm |
| September | 21.6 °C | 30.6 °C | 148.34 mm |
| October | 16.3 °C | 26.3 °C | 107.7 mm |
| November | 10.6 °C | 21.3 °C | 110.24 mm |
| December | 6.9 °C | 17.3 °C | 121.92 mm |
| Annual | 15.2 °C | 25 °C | 1728.73 mm |
| Average First Frost Date | Jan. 11 - Jan. 20 |
| Average Last Frost Date | Frost Rare |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |