Mackinac Island, Michigan has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.1 °C (low) to 10.2 °C (high). Annual precipitation averages 810 Millimeters. Mackinac Island is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11.1 °C | -3.9 °C | 49.02 mm |
| February | -11.4 °C | -3.2 °C | 33.53 mm |
| March | -7.2 °C | 1.5 °C | 42.67 mm |
| April | -0.7 °C | 7.9 °C | 67.56 mm |
| May | 5.3 °C | 14.7 °C | 71.88 mm |
| June | 11.1 °C | 20.6 °C | 74.68 mm |
| July | 14.8 °C | 23.8 °C | 73.66 mm |
| August | 14.7 °C | 23.4 °C | 79.25 mm |
| September | 11.1 °C | 19.6 °C | 86.87 mm |
| October | 4.9 °C | 12.3 °C | 106.17 mm |
| November | -0.4 °C | 5.4 °C | 66.8 mm |
| December | -6.1 °C | -0.2 °C | 57.91 mm |
| Annual | 2.1 °C | 10.2 °C | 810 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |