Boy River, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 29.5 °F (low) to 50.5 °F (high). Annual precipitation averages 27.2 Inches. Boy River is located in USDA Plant Hardiness Zone 3b. 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 | -2.3 °F | 17.8 °F | 0.73 in. |
| February | 0.9 °F | 24.1 °F | 0.69 in. |
| March | 14.5 °F | 37.1 °F | 1.17 in. |
| April | 28.6 °F | 51.3 °F | 1.96 in. |
| May | 41.5 °F | 65.1 °F | 3.09 in. |
| June | 52.1 °F | 74.2 °F | 4.21 in. |
| July | 56.9 °F | 78.6 °F | 4.24 in. |
| August | 54.4 °F | 76.9 °F | 3.32 in. |
| September | 46.1 °F | 68.2 °F | 3.1 in. |
| October | 34.1 °F | 52.9 °F | 2.59 in. |
| November | 21.0 °F | 36.3 °F | 1.18 in. |
| December | 6.7 °F | 23.1 °F | 0.91 in. |
| Annual | 29.5 °F | 50.5 °F | 27.19 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 3b : -35°F to -30°F |
| Plant Hardiness Zone - 2012 | Zone 3b : -35°F to -30°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |