Roby, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.6 °C (low) to 25.1 °C (high). Annual precipitation averages 596.6 Millimeters. Roby 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 | -0.7 °C | 13.8 °C | 27.94 mm |
| February | 1.1 °C | 16.1 °C | 29.97 mm |
| March | 5.3 °C | 20.8 °C | 43.69 mm |
| April | 9.7 °C | 25.8 °C | 42.67 mm |
| May | 15.4 °C | 29.8 °C | 78.49 mm |
| June | 20.1 °C | 33.7 °C | 83.06 mm |
| July | 21.9 °C | 35.6 °C | 40.89 mm |
| August | 21.3 °C | 35.2 °C | 60.2 mm |
| September | 17.2 °C | 30.8 °C | 72.64 mm |
| October | 11.1 °C | 25.9 °C | 53.59 mm |
| November | 4.7 °C | 19.2 °C | 31.75 mm |
| December | 0.2 °C | 14.3 °C | 31.75 mm |
| Annual | 10.6 °C | 25.1 °C | 596.64 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 | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |