Grawn, Michigan has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.2 °C (low) to 12.8 °C (high). Annual precipitation averages 887.2 Millimeters. Grawn is located in USDA Plant Hardiness Zone 6a. 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 | -9.8 °C | -2.3 °C | 62.48 mm |
| February | -9.9 °C | -0.9 °C | 45.47 mm |
| March | -6.1 °C | 4.7 °C | 52.07 mm |
| April | -0.2 °C | 11.8 °C | 80.77 mm |
| May | 5.9 °C | 19.2 °C | 78.99 mm |
| June | 11.6 °C | 24.7 °C | 75.44 mm |
| July | 14.2 °C | 27 °C | 73.66 mm |
| August | 13.6 °C | 26.1 °C | 81.53 mm |
| September | 9.7 °C | 21.9 °C | 89.92 mm |
| October | 3.9 °C | 14.4 °C | 104.39 mm |
| November | -1.2 °C | 6.7 °C | 75.95 mm |
| December | -5.9 °C | 0.6 °C | 66.55 mm |
| Annual | 2.2 °C | 12.8 °C | 887.22 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°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 |