Rockwall, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 12.7 °C (low) to 24.3 °C (high). Annual precipitation averages 1036.8 Millimeters. Rockwall 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 | 1.7 °C | 13.1 °C | 65.02 mm |
| February | 3.7 °C | 15.4 °C | 74.17 mm |
| March | 7.8 °C | 19.6 °C | 95.25 mm |
| April | 12 °C | 23.8 °C | 90.68 mm |
| May | 17.2 °C | 27.9 °C | 124.21 mm |
| June | 21.6 °C | 32.4 °C | 97.28 mm |
| July | 23.3 °C | 34.7 °C | 53.09 mm |
| August | 23.1 °C | 34.9 °C | 63.75 mm |
| September | 19.2 °C | 31.3 °C | 78.23 mm |
| October | 12.9 °C | 25.7 °C | 119.38 mm |
| November | 7.3 °C | 19.1 °C | 84.84 mm |
| December | 2.8 °C | 14.2 °C | 90.93 mm |
| Annual | 12.7 °C | 24.3 °C | 1036.83 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 1 - Mar. 10 |
| Average Days With Frost | 30-40 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 | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |