Mandan, North Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 31.2 °F (low) to 55 °F (high). Annual precipitation averages 18.3 Inches. 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 | 2.5 °F | 23.4 °F | 0.44 in. |
| February | 7.6 °F | 28.2 °F | 0.45 in. |
| March | 18.3 °F | 40.8 °F | 0.64 in. |
| April | 30.0 °F | 55.6 °F | 1.15 in. |
| May | 42.3 °F | 67.8 °F | 2.6 in. |
| June | 52.8 °F | 77.1 °F | 3.31 in. |
| July | 57.9 °F | 83.9 °F | 3.2 in. |
| August | 55.6 °F | 83.1 °F | 2.19 in. |
| September | 46.0 °F | 73.5 °F | 1.67 in. |
| October | 32.9 °F | 57.5 °F | 1.41 in. |
| November | 19.7 °F | 41.0 °F | 0.7 in. |
| December | 8.9 °F | 28.4 °F | 0.56 in. |
| Annual | 31.2 °F | 55 °F | 18.32 in. |
| 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 : -30°F to -25°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |