Bismarck, 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 54.5 °F (high). Annual precipitation averages 19.1 Inches. Bismarck 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 | 2.6 °F | 22.8 °F | 0.51 in. |
| February | 7.2 °F | 27.4 °F | 0.49 in. |
| March | 18.2 °F | 40.0 °F | 0.74 in. |
| April | 30.0 °F | 55.1 °F | 1.21 in. |
| May | 42.4 °F | 67.4 °F | 2.61 in. |
| June | 52.8 °F | 76.8 °F | 3.37 in. |
| July | 57.9 °F | 83.5 °F | 3.3 in. |
| August | 55.6 °F | 82.8 °F | 2.34 in. |
| September | 46.0 °F | 73.1 °F | 1.75 in. |
| October | 32.9 °F | 57.1 °F | 1.38 in. |
| November | 19.7 °F | 40.5 °F | 0.74 in. |
| December | 8.8 °F | 27.9 °F | 0.63 in. |
| Annual | 31.2 °F | 54.5 °F | 19.07 in. |
| 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 : -30°F to -25°F |
| Plant Hardiness Zone - 2012 | Zone 4a : -30°F to -25°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |