Marietta, Mississippi has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.4 °C (low) to 22.7 °C (high). Annual precipitation averages 1495.5 Millimeters. Marietta 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 | -0.4 °C | 10.7 °C | 130.3 mm |
| February | 1.2 °C | 13.2 °C | 131.57 mm |
| March | 5.2 °C | 18.2 °C | 137.92 mm |
| April | 9.7 °C | 23.3 °C | 140.21 mm |
| May | 15.1 °C | 27.3 °C | 141.22 mm |
| June | 19.4 °C | 31 °C | 122.68 mm |
| July | 21.3 °C | 32.6 °C | 115.82 mm |
| August | 20.6 °C | 32.6 °C | 104.9 mm |
| September | 16.7 °C | 29.7 °C | 104.9 mm |
| October | 9.9 °C | 23.9 °C | 99.57 mm |
| November | 4.2 °C | 17.3 °C | 110.49 mm |
| December | 1.3 °C | 12.1 °C | 155.96 mm |
| Annual | 10.4 °C | 22.7 °C | 1495.54 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 7b : -15°C to -12.2°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |