Mandan, North Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.4 °C (low) to 12.8 °C (high). Annual precipitation averages 465.3 Millimeters. Mandan is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -16.4 °C | -4.8 °C | 11.18 mm |
| February | -13.6 °C | -2.1 °C | 11.43 mm |
| March | -7.6 °C | 4.9 °C | 16.26 mm |
| April | -1.1 °C | 13.1 °C | 29.21 mm |
| May | 5.7 °C | 19.9 °C | 66.04 mm |
| June | 11.6 °C | 25.1 °C | 84.07 mm |
| July | 14.4 °C | 28.8 °C | 81.28 mm |
| August | 13.1 °C | 28.4 °C | 55.63 mm |
| September | 7.8 °C | 23.1 °C | 42.42 mm |
| October | 0.5 °C | 14.2 °C | 35.81 mm |
| November | -6.8 °C | 5 °C | 17.78 mm |
| December | -12.8 °C | -2 °C | 14.22 mm |
| Annual | -0.4 °C | 12.8 °C | 465.33 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 1 - May 10 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |