Hillsboro, North Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.7 °C (low) to 10.5 °C (high). Annual precipitation averages 588 Millimeters. Hillsboro is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -18.7 °C | -8.9 °C | 15.75 mm |
| February | -16.6 °C | -6.1 °C | 15.24 mm |
| March | -8.9 °C | 1 °C | 24.13 mm |
| April | -0.6 °C | 11.2 °C | 32.26 mm |
| May | 6.4 °C | 19.3 °C | 73.66 mm |
| June | 12.9 °C | 24.6 °C | 103.63 mm |
| July | 14.8 °C | 27.1 °C | 92.96 mm |
| August | 13.1 °C | 26.5 °C | 68.07 mm |
| September | 8.2 °C | 21.7 °C | 70.36 mm |
| October | 1.4 °C | 12.8 °C | 51.56 mm |
| November | -6.7 °C | 2.9 °C | 20.83 mm |
| December | -14.2 °C | -5.6 °C | 19.56 mm |
| Annual | -0.7 °C | 10.5 °C | 588.01 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4a : -34.4°C to -31.7°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |