Roy Lake, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 29.8 °F (low) to 49.9 °F (high). Annual precipitation averages 25.9 Inches. Roy Lake is located in USDA Plant Hardiness Zone 3b. 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 | -2.9 °F | 17.3 °F | 0.65 in. |
| February | 0.2 °F | 22.5 °F | 0.63 in. |
| March | 14.3 °F | 35.5 °F | 1.06 in. |
| April | 28.6 °F | 50.8 °F | 1.63 in. |
| May | 42.5 °F | 64.4 °F | 3.1 in. |
| June | 53.5 °F | 73.7 °F | 4.54 in. |
| July | 58.0 °F | 78.8 °F | 3.92 in. |
| August | 55.6 °F | 76.9 °F | 2.95 in. |
| September | 47.0 °F | 68.1 °F | 2.96 in. |
| October | 34.5 °F | 52.6 °F | 2.59 in. |
| November | 20.2 °F | 35.7 °F | 1.1 in. |
| December | 6.5 °F | 22.7 °F | 0.8 in. |
| Annual | 29.8 °F | 49.9 °F | 25.93 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 3b : -35°F to -30°F |
| Plant Hardiness Zone - 2012 | Zone 3b : -35°F to -30°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |