Walhalla, North Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -1.7 °C (low) to 9.4 °C (high). Annual precipitation averages 559.1 Millimeters. Walhalla 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 Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -19.2 °C | -9.9 °C | 15.49 mm |
| February | -17.4 °C | -7.2 °C | 14.48 mm |
| March | -9.8 °C | -0.3 °C | 20.57 mm |
| April | -2.1 °C | 10 °C | 24.89 mm |
| May | 5.1 °C | 18.2 °C | 82.04 mm |
| June | 11.7 °C | 23.6 °C | 95 mm |
| July | 14.1 °C | 25.8 °C | 83.82 mm |
| August | 12.2 °C | 25.8 °C | 68.58 mm |
| September | 7.4 °C | 20.7 °C | 61.47 mm |
| October | 0.6 °C | 11.6 °C | 44.96 mm |
| November | -7.4 °C | 1.6 °C | 26.42 mm |
| December | -15.2 °C | -6.6 °C | 21.34 mm |
| Annual | -1.7 °C | 9.4 °C | 559.06 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4a : -34.4°C to -31.7°C |
| Plant Hardiness Zone - 2012 | Zone 3b : -37.2°C to -34.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |