Willow City, North Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -2.8 °C (low) to 10 °C (high). Annual precipitation averages 466.3 Millimeters. Willow City is located in USDA Plant Hardiness Zone 3b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -20.3 °C | -9.2 °C | 11.68 mm |
| February | -18.1 °C | -6.3 °C | 10.92 mm |
| March | -10.8 °C | 0.6 °C | 18.8 mm |
| April | -2.6 °C | 11.1 °C | 24.38 mm |
| May | 4.6 °C | 18.8 °C | 61.98 mm |
| June | 10.7 °C | 23.7 °C | 96.77 mm |
| July | 12.9 °C | 26.6 °C | 75.18 mm |
| August | 11.3 °C | 26.7 °C | 59.18 mm |
| September | 5.8 °C | 21.1 °C | 42.16 mm |
| October | -1.4 °C | 12 °C | 32 mm |
| November | -9.4 °C | 1.6 °C | 17.78 mm |
| December | -16.6 °C | -6.2 °C | 15.49 mm |
| Annual | -2.8 °C | 10 °C | 466.32 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 3b : -37.2°C to -34.4°C |
| Plant Hardiness Zone - 2012 | Zone 3a : -40°C to -37.2°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |