Ortonville, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.7 °C (low) to 12.3 °C (high). Annual precipitation averages 637.8 Millimeters. Ortonville is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -16.1 °C | -5.7 °C | 17.02 mm |
| February | -14.3 °C | -3.4 °C | 17.02 mm |
| March | -7.1 °C | 3.6 °C | 29.46 mm |
| April | 0.3 °C | 12.6 °C | 61.98 mm |
| May | 7.7 °C | 20.1 °C | 72.39 mm |
| June | 13.9 °C | 25.5 °C | 97.03 mm |
| July | 15.9 °C | 27.7 °C | 100.84 mm |
| August | 14.3 °C | 26.8 °C | 80.52 mm |
| September | 9.3 °C | 22.8 °C | 62.48 mm |
| October | 2.1 °C | 14.4 °C | 56.9 mm |
| November | -5.2 °C | 5.4 °C | 24.89 mm |
| December | -12.1 °C | -2.6 °C | 17.27 mm |
| Annual | 0.7 °C | 12.3 °C | 637.8 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |