Royalton, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 32.1 °F (low) to 53.1 °F (high). Annual precipitation averages 28.7 Inches. Royalton is located in USDA Plant Hardiness Zone 4a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 1.5 °F | 20.6 °F | 0.66 in. |
| February | 4.7 °F | 25.8 °F | 0.74 in. |
| March | 18.0 °F | 38.8 °F | 1.38 in. |
| April | 31.2 °F | 53.9 °F | 2.45 in. |
| May | 44.3 °F | 67.5 °F | 3.48 in. |
| June | 54.8 °F | 76.8 °F | 4.38 in. |
| July | 59.1 °F | 81.4 °F | 4.09 in. |
| August | 56.2 °F | 79.2 °F | 3.72 in. |
| September | 47.9 °F | 71.1 °F | 2.89 in. |
| October | 35.6 °F | 56.5 °F | 2.75 in. |
| November | 22.4 °F | 39.6 °F | 1.24 in. |
| December | 9.7 °F | 26.0 °F | 0.93 in. |
| Annual | 32.1 °F | 53.1 °F | 28.71 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| 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 |