Hillsboro, West Virginia has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.3 °C (low) to 16.3 °C (high). Annual precipitation averages 1141.2 Millimeters. Hillsboro is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.4 °C | 3.6 °C | 87.12 mm |
| February | -6.4 °C | 5.8 °C | 77.47 mm |
| March | -2.9 °C | 10.4 °C | 105.92 mm |
| April | 2 °C | 17.1 °C | 102.11 mm |
| May | 7.5 °C | 21.8 °C | 120.9 mm |
| June | 12.2 °C | 25.4 °C | 102.62 mm |
| July | 14.6 °C | 27.3 °C | 106.43 mm |
| August | 14.1 °C | 26.6 °C | 94.49 mm |
| September | 10.4 °C | 23.6 °C | 89.92 mm |
| October | 3.6 °C | 17.6 °C | 75.18 mm |
| November | -2.3 °C | 11.1 °C | 78.49 mm |
| December | -5.4 °C | 5.5 °C | 100.58 mm |
| Annual | 3.3 °C | 16.3 °C | 1141.23 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |