Hartland, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 35.5 °F (low) to 54.4 °F (high). Annual precipitation averages 35.2 Inches. 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 | 6.1 °F | 22.8 °F | 0.92 in. |
| February | 9.7 °F | 27.0 °F | 0.9 in. |
| March | 22.3 °F | 39.4 °F | 1.84 in. |
| April | 34.8 °F | 55.2 °F | 3.41 in. |
| May | 47.3 °F | 67.6 °F | 4.49 in. |
| June | 58.4 °F | 77.9 °F | 5.3 in. |
| July | 61.7 °F | 81.2 °F | 4.93 in. |
| August | 59.0 °F | 78.8 °F | 4.32 in. |
| September | 50.5 °F | 72.8 °F | 3.86 in. |
| October | 37.5 °F | 58.8 °F | 2.44 in. |
| November | 25.4 °F | 42.6 °F | 1.53 in. |
| December | 13.3 °F | 28.3 °F | 1.23 in. |
| Annual | 35.5 °F | 54.4 °F | 35.17 in. |
| 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 : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |