Round Rock, Texas has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 13.5 °C (low) to 26.2 °C (high). Annual precipitation averages 945.1 Millimeters. Round Rock is located in USDA Plant Hardiness Zone 9a. The growing season typically runs from the last frost around Feb. 21 - Feb. 29 through the first frost around Nov. 21 - Nov. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 3.2 °C | 16.3 °C | 66.8 mm |
| February | 5.2 °C | 18.2 °C | 53.34 mm |
| March | 9.1 °C | 22 °C | 76.96 mm |
| April | 12.9 °C | 26 °C | 67.31 mm |
| May | 18 °C | 29.6 °C | 114.55 mm |
| June | 21.7 °C | 33.2 °C | 91.44 mm |
| July | 22.8 °C | 34.9 °C | 67.82 mm |
| August | 22.6 °C | 35.6 °C | 61.72 mm |
| September | 19.7 °C | 32.3 °C | 87.38 mm |
| October | 14.1 °C | 27.6 °C | 108.2 mm |
| November | 8.2 °C | 21.3 °C | 78.99 mm |
| December | 4.1 °C | 16.9 °C | 70.61 mm |
| Annual | 13.5 °C | 26.2 °C | 945.12 mm |
| Average First Frost Date | Nov. 21 - Nov. 30 |
| Average Last Frost Date | Feb. 21 - Feb. 29 |
| Average Days With Frost | 10-20 Days |
| Plant Hardiness Zone | Zone 9a : -6.7°C to -3.9°C |
| Plant Hardiness Zone - 2012 | Zone 8b : -9.4°C to -6.7°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |