Grand Marais, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.3 °C (low) to 8.3 °C (high). Annual precipitation averages 721.6 Millimeters. Grand Marais is located in USDA Plant Hardiness Zone 5a. 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 | -14.8 °C | -5.7 °C | 36.07 mm |
| February | -13.9 °C | -3.5 °C | 28.19 mm |
| March | -8.1 °C | 1.4 °C | 33.02 mm |
| April | -1.1 °C | 6.8 °C | 54.86 mm |
| May | 3.7 °C | 12.3 °C | 69.6 mm |
| June | 7.4 °C | 16.9 °C | 94.74 mm |
| July | 11.8 °C | 21.2 °C | 89.92 mm |
| August | 12.9 °C | 21.4 °C | 66.8 mm |
| September | 9.4 °C | 17.4 °C | 71.88 mm |
| October | 3.3 °C | 10.7 °C | 73.91 mm |
| November | -3.5 °C | 3.7 °C | 55.37 mm |
| December | -10.6 °C | -2.7 °C | 47.24 mm |
| Annual | -0.3 °C | 8.3 °C | 721.6 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 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |