Gretna, Florida has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 55.7 °F (low) to 78.4 °F (high). Annual precipitation averages 56.5 Inches. Gretna is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Mar. 1 - Mar. 10 through the first frost around Nov. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 39.0 °F | 62.2 °F | 4.84 in. |
| February | 41.9 °F | 66.2 °F | 4.79 in. |
| March | 47.1 °F | 72.6 °F | 5.19 in. |
| April | 53.6 °F | 78.5 °F | 4.31 in. |
| May | 62.0 °F | 85.9 °F | 3.51 in. |
| June | 69.2 °F | 89.8 °F | 6.19 in. |
| July | 71.2 °F | 91.0 °F | 6.27 in. |
| August | 71.3 °F | 90.4 °F | 5.86 in. |
| September | 67.3 °F | 87.3 °F | 5.08 in. |
| October | 57.4 °F | 80.4 °F | 3.19 in. |
| November | 46.9 °F | 71.4 °F | 3.37 in. |
| December | 42.0 °F | 64.5 °F | 3.92 in. |
| Annual | 55.7 °F | 78.4 °F | 56.52 in. |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| Average Last Frost Date | Mar. 1 - Mar. 10 |
| Average Days With Frost | 20-30 Days |
| Plant Hardiness Zone | Zone 9a : 20°F to 25°F |
| Plant Hardiness Zone - 2012 | Zone 8b : 15°F to 20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |