Grand Marais, Minnesota has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 31.5 °F (low) to 47 °F (high). Annual precipitation averages 28.4 Inches. 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 | 5.3 °F | 21.8 °F | 1.42 in. |
| February | 7.0 °F | 25.7 °F | 1.11 in. |
| March | 17.5 °F | 34.6 °F | 1.3 in. |
| April | 30.1 °F | 44.3 °F | 2.16 in. |
| May | 38.6 °F | 54.1 °F | 2.74 in. |
| June | 45.3 °F | 62.4 °F | 3.73 in. |
| July | 53.3 °F | 70.2 °F | 3.54 in. |
| August | 55.3 °F | 70.5 °F | 2.63 in. |
| September | 49.0 °F | 63.4 °F | 2.83 in. |
| October | 37.9 °F | 51.3 °F | 2.91 in. |
| November | 25.7 °F | 38.6 °F | 2.18 in. |
| December | 13.0 °F | 27.1 °F | 1.86 in. |
| Annual | 31.5 °F | 47 °F | 28.41 in. |
| 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 : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |