Roscoe, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.6 °C (low) to 13.7 °C (high). Annual precipitation averages 529.1 Millimeters. Roscoe 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 Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.8 °C | 3.2 °C | 21.34 mm |
| February | -8.2 °C | 3.3 °C | 25.65 mm |
| March | -4.7 °C | 7.8 °C | 36.83 mm |
| April | -1.2 °C | 11.7 °C | 62.74 mm |
| May | 3.3 °C | 16.4 °C | 101.35 mm |
| June | 7.7 °C | 21.9 °C | 68.58 mm |
| July | 11.4 °C | 27.7 °C | 38.35 mm |
| August | 10.9 °C | 27.3 °C | 28.7 mm |
| September | 6.3 °C | 21.6 °C | 40.89 mm |
| October | 0.8 °C | 13.8 °C | 52.32 mm |
| November | -4 °C | 7.1 °C | 28.7 mm |
| December | -7.7 °C | 2.6 °C | 23.62 mm |
| Annual | 0.6 °C | 13.7 °C | 529.07 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| 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 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |