Mercer, North Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 30.1 °F (low) to 52.1 °F (high). Annual precipitation averages 17.9 Inches. Mercer 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 | 1.1 °F | 19.6 °F | 0.5 in. |
| February | 4.6 °F | 24.1 °F | 0.44 in. |
| March | 16.3 °F | 36.5 °F | 0.66 in. |
| April | 29.0 °F | 53.0 °F | 1.01 in. |
| May | 41.6 °F | 66.0 °F | 2.6 in. |
| June | 52.3 °F | 75.0 °F | 3.55 in. |
| July | 57.3 °F | 81.6 °F | 2.81 in. |
| August | 54.9 °F | 81.4 °F | 2.0 in. |
| September | 45.4 °F | 71.3 °F | 1.73 in. |
| October | 32.5 °F | 55.1 °F | 1.36 in. |
| November | 18.8 °F | 37.6 °F | 0.66 in. |
| December | 7.2 °F | 24.4 °F | 0.59 in. |
| Annual | 30.1 °F | 52.1 °F | 17.91 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 | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |