Marietta, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 11.6 °C (low) to 24.3 °C (high). Annual precipitation averages 1290.1 Millimeters. Marietta is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 1 - Mar. 10 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.1 °C | 13.2 °C | 95 mm |
| February | 2.7 °C | 15.3 °C | 113.03 mm |
| March | 6.8 °C | 19.8 °C | 120.14 mm |
| April | 10.9 °C | 24.1 °C | 114.81 mm |
| May | 16.2 °C | 28.1 °C | 129.54 mm |
| June | 20.4 °C | 31.9 °C | 106.17 mm |
| July | 22.1 °C | 34.2 °C | 89.66 mm |
| August | 21.6 °C | 34.5 °C | 72.9 mm |
| September | 18.1 °C | 31.2 °C | 105.16 mm |
| October | 11.3 °C | 25.4 °C | 121.92 mm |
| November | 6.1 °C | 19.1 °C | 102.36 mm |
| December | 2.1 °C | 14.3 °C | 119.38 mm |
| Annual | 11.6 °C | 24.3 °C | 1290.07 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 1 - Mar. 10 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8a : -12.2°C to -9.4°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |