Forest River, North Dakota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 30 °F (low) to 49.9 °F (high). Annual precipitation averages 21.6 Inches. Forest River 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 | -2.3 °F | 14.8 °F | 0.54 in. |
| February | 1.5 °F | 19.9 °F | 0.52 in. |
| March | 15.1 °F | 32.6 °F | 0.84 in. |
| April | 30.2 °F | 50.9 °F | 1.08 in. |
| May | 42.8 °F | 65.8 °F | 3.13 in. |
| June | 54.4 °F | 75.3 °F | 3.89 in. |
| July | 58.0 °F | 79.8 °F | 3.19 in. |
| August | 55.1 °F | 79.4 °F | 2.81 in. |
| September | 46.1 °F | 70.3 °F | 2.23 in. |
| October | 33.8 °F | 54.1 °F | 1.77 in. |
| November | 19.1 °F | 35.5 °F | 0.86 in. |
| December | 5.6 °F | 20.9 °F | 0.75 in. |
| Annual | 30 °F | 49.9 °F | 21.61 in. |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| 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 | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |