Roscommon, Michigan has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.1 °C (low) to 12.6 °C (high). Annual precipitation averages 863.6 Millimeters. Roscommon is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -12.4 °C | -2.8 °C | 57.4 mm |
| February | -12.8 °C | -1.1 °C | 41.15 mm |
| March | -8.6 °C | 4.6 °C | 49.28 mm |
| April | -1.8 °C | 11.8 °C | 81.53 mm |
| May | 4.9 °C | 19.3 °C | 88.14 mm |
| June | 10.2 °C | 24.7 °C | 89.66 mm |
| July | 12.4 °C | 26.9 °C | 78.23 mm |
| August | 11.4 °C | 25.8 °C | 83.06 mm |
| September | 7.1 °C | 21.7 °C | 77.98 mm |
| October | 1.7 °C | 13.8 °C | 91.95 mm |
| November | -3.2 °C | 6.2 °C | 68.83 mm |
| December | -7.9 °C | 0 °C | 56.39 mm |
| Annual | 0.1 °C | 12.6 °C | 863.6 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 21 - May 31 |
| 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 | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |