Royalton, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.1 °C (low) to 11.7 °C (high). Annual precipitation averages 729.2 Millimeters. 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 | -16.9 °C | -6.3 °C | 16.76 mm |
| February | -15.2 °C | -3.4 °C | 18.8 mm |
| March | -7.8 °C | 3.8 °C | 35.05 mm |
| April | -0.4 °C | 12.2 °C | 62.23 mm |
| May | 6.8 °C | 19.7 °C | 88.39 mm |
| June | 12.7 °C | 24.9 °C | 111.25 mm |
| July | 15.1 °C | 27.4 °C | 103.89 mm |
| August | 13.4 °C | 26.2 °C | 94.49 mm |
| September | 8.8 °C | 21.7 °C | 73.41 mm |
| October | 2 °C | 13.6 °C | 69.85 mm |
| November | -5.3 °C | 4.2 °C | 31.5 mm |
| December | -12.4 °C | -3.3 °C | 23.62 mm |
| Annual | 0.1 °C | 11.7 °C | 729.24 mm |
| 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 : -34.4°C to -31.7°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |