Hillsboro, Missouri has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.5 °C (low) to 19 °C (high). Annual precipitation averages 1111.8 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.3 °C | 5 °C | 70.36 mm |
| February | -3.4 °C | 7.8 °C | 65.53 mm |
| March | 1.2 °C | 13.1 °C | 96.01 mm |
| April | 7.2 °C | 19.7 °C | 124.21 mm |
| May | 12.7 °C | 24.3 °C | 129.54 mm |
| June | 17.5 °C | 28.8 °C | 103.89 mm |
| July | 19.7 °C | 31 °C | 99.57 mm |
| August | 18.7 °C | 30.6 °C | 93.47 mm |
| September | 14.3 °C | 26.7 °C | 93.22 mm |
| October | 7.7 °C | 20.6 °C | 77.47 mm |
| November | 1.9 °C | 13.1 °C | 85.6 mm |
| December | -2.6 °C | 6.9 °C | 72.9 mm |
| Annual | 7.5 °C | 19 °C | 1111.77 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 75-100 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 | Cfa - Humid Subtropical Climate |