Round Hill, Virginia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 6.1 °C (low) to 18.5 °C (high). Annual precipitation averages 1109 Millimeters. Round Hill is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.9 °C | 5.6 °C | 76.2 mm |
| February | -4 °C | 7.4 °C | 59.18 mm |
| March | -0.4 °C | 12 °C | 94.23 mm |
| April | 5.1 °C | 18.7 °C | 93.22 mm |
| May | 10.4 °C | 23.4 °C | 117.09 mm |
| June | 15.4 °C | 28 °C | 113.03 mm |
| July | 17.9 °C | 30.6 °C | 97.03 mm |
| August | 16.9 °C | 29.6 °C | 81.28 mm |
| September | 12.9 °C | 25.9 °C | 119.63 mm |
| October | 6.3 °C | 19.7 °C | 90.42 mm |
| November | 1 °C | 13.3 °C | 77.72 mm |
| December | -2.9 °C | 7.7 °C | 89.92 mm |
| Annual | 6.1 °C | 18.5 °C | 1108.95 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |