Harriston, Virginia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 6.5 °C (low) to 19 °C (high). Annual precipitation averages 1077.7 Millimeters. Harriston is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.3 °C | 6.8 °C | 76.45 mm |
| February | -3.2 °C | 8.7 °C | 58.17 mm |
| March | 0.2 °C | 13.1 °C | 90.42 mm |
| April | 5.6 °C | 19.5 °C | 89.66 mm |
| May | 10.9 °C | 23.7 °C | 100.08 mm |
| June | 15.8 °C | 28.1 °C | 104.65 mm |
| July | 18 °C | 30 °C | 99.82 mm |
| August | 17.1 °C | 29.3 °C | 86.87 mm |
| September | 13.2 °C | 25.8 °C | 125.73 mm |
| October | 6.6 °C | 20 °C | 83.06 mm |
| November | 0.8 °C | 13.9 °C | 83.82 mm |
| December | -2.5 °C | 8.6 °C | 78.99 mm |
| Annual | 6.5 °C | 19 °C | 1077.72 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |