Hillsboro, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.1 °C (low) to 16.8 °C (high). Annual precipitation averages 1157.5 Millimeters. Hillsboro is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.9 °C | 3.1 °C | 86.11 mm |
| February | -4.6 °C | 5.2 °C | 77.98 mm |
| March | -0.3 °C | 10.4 °C | 103.38 mm |
| April | 5.2 °C | 17.3 °C | 121.16 mm |
| May | 11.2 °C | 22.2 °C | 122.17 mm |
| June | 16 °C | 26.8 °C | 115.32 mm |
| July | 17.7 °C | 28.6 °C | 109.47 mm |
| August | 16.7 °C | 27.9 °C | 95.5 mm |
| September | 12.7 °C | 25 °C | 82.04 mm |
| October | 6.6 °C | 18.6 °C | 78.49 mm |
| November | 1 °C | 11.3 °C | 79.25 mm |
| December | -3 °C | 5.3 °C | 86.61 mm |
| Annual | 6.1 °C | 16.8 °C | 1157.48 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 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 | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |