Alsen, North Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -2.5 °C (low) to 8.8 °C (high). Annual precipitation averages 507.5 Millimeters. Alsen 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 | -20.2 °C | -10.3 °C | 12.95 mm |
| February | -18.6 °C | -7.7 °C | 12.19 mm |
| March | -11 °C | -0.8 °C | 18.29 mm |
| April | -2.4 °C | 9.3 °C | 24.89 mm |
| May | 4.7 °C | 17.6 °C | 73.66 mm |
| June | 11.1 °C | 22.7 °C | 95 mm |
| July | 13.3 °C | 25.3 °C | 81.28 mm |
| August | 11.9 °C | 25.3 °C | 65.28 mm |
| September | 6.6 °C | 20.1 °C | 50.29 mm |
| October | -0.6 °C | 11.1 °C | 37.59 mm |
| November | -8.7 °C | 0.8 °C | 19.3 mm |
| December | -16.3 °C | -7.3 °C | 16.76 mm |
| Annual | -2.5 °C | 8.8 °C | 507.48 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 3b : -37.2°C to -34.4°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |