Millboro, Virginia has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 5.9 °C (low) to 18.2 °C (high). Annual precipitation averages 1144 Millimeters. Millboro 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.6 °C | 5.6 °C | 85.85 mm |
| February | -3.7 °C | 7.8 °C | 72.9 mm |
| March | -0.2 °C | 12.4 °C | 96.52 mm |
| April | 5.2 °C | 19.1 °C | 96.77 mm |
| May | 10.3 °C | 23.4 °C | 116.33 mm |
| June | 14.7 °C | 27.2 °C | 121.92 mm |
| July | 16.8 °C | 29.3 °C | 110.24 mm |
| August | 16.1 °C | 28.5 °C | 90.68 mm |
| September | 12.5 °C | 25.1 °C | 100.84 mm |
| October | 6.2 °C | 19.4 °C | 79.25 mm |
| November | 0.6 °C | 13.1 °C | 82.55 mm |
| December | -2.8 °C | 7.6 °C | 90.17 mm |
| Annual | 5.9 °C | 18.2 °C | 1144.02 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 |