Kilmarnock, Virginia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 10.1 °C (low) to 20.3 °C (high). Annual precipitation averages 1228.3 Millimeters. Kilmarnock is located in USDA Plant Hardiness Zone 8a. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -1.1 °C | 8.9 °C | 89.66 mm |
| February | -0.6 °C | 10.3 °C | 72.14 mm |
| March | 2.7 °C | 14.3 °C | 108.2 mm |
| April | 8.3 °C | 20.1 °C | 86.87 mm |
| May | 13.8 °C | 24.4 °C | 98.55 mm |
| June | 18.9 °C | 28.8 °C | 112.01 mm |
| July | 21.6 °C | 31.3 °C | 125.73 mm |
| August | 21 °C | 30 °C | 132.59 mm |
| September | 17.9 °C | 27.1 °C | 122.43 mm |
| October | 11.8 °C | 21.5 °C | 104.9 mm |
| November | 5.7 °C | 15.8 °C | 78.99 mm |
| December | 1.4 °C | 11.2 °C | 96.27 mm |
| Annual | 10.1 °C | 20.3 °C | 1228.34 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| 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 |