Hartland, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2 °C (low) to 12.4 °C (high). Annual precipitation averages 893.3 Millimeters. Hartland is located in USDA Plant Hardiness Zone 5a. 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 | -14.4 °C | -5.1 °C | 23.37 mm |
| February | -12.4 °C | -2.8 °C | 22.86 mm |
| March | -5.4 °C | 4.1 °C | 46.74 mm |
| April | 1.6 °C | 12.9 °C | 86.61 mm |
| May | 8.5 °C | 19.8 °C | 114.05 mm |
| June | 14.7 °C | 25.5 °C | 134.62 mm |
| July | 16.5 °C | 27.3 °C | 125.22 mm |
| August | 15 °C | 26 °C | 109.73 mm |
| September | 10.3 °C | 22.7 °C | 98.04 mm |
| October | 3.1 °C | 14.9 °C | 61.98 mm |
| November | -3.7 °C | 5.9 °C | 38.86 mm |
| December | -10.4 °C | -2.1 °C | 31.24 mm |
| Annual | 2 °C | 12.4 °C | 893.32 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 5a : -28.9°C to -26.1°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 |