Round Mountain, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 12.8 °C (low) to 25.2 °C (high). Annual precipitation averages 793.8 Millimeters. Round Mountain is located in USDA Plant Hardiness Zone 8b. The growing season typically runs from the last frost around Mar. 11 - Mar. 20 through the first frost around Nov. 11 - Nov. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.9 °C | 15.4 °C | 50.29 mm |
| February | 4.8 °C | 17.4 °C | 48.77 mm |
| March | 8.6 °C | 21.3 °C | 63.25 mm |
| April | 12.4 °C | 25.2 °C | 59.18 mm |
| May | 17.2 °C | 28.5 °C | 105.16 mm |
| June | 20.6 °C | 32.1 °C | 72.39 mm |
| July | 21.8 °C | 34 °C | 52.58 mm |
| August | 21.8 °C | 34.8 °C | 46.23 mm |
| September | 18.7 °C | 31.1 °C | 86.87 mm |
| October | 13.4 °C | 26.4 °C | 86.11 mm |
| November | 8 °C | 20.4 °C | 71.37 mm |
| December | 3.5 °C | 16.1 °C | 51.56 mm |
| Annual | 12.8 °C | 25.2 °C | 793.76 mm |
| Average First Frost Date | Nov. 11 - Nov. 20 |
| Average Last Frost Date | Mar. 11 - Mar. 20 |
| Average Days With Frost | 40-50 Days |
| Plant Hardiness Zone | Zone 8b : -9.4°C to -6.7°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |