Sand Coulee, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 0.7 °C (low) to 14.5 °C (high). Annual precipitation averages 401.6 Millimeters. Sand Coulee is located in USDA Plant Hardiness Zone 4b. 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 | -9.1 °C | 2.4 °C | 15.49 mm |
| February | -8.6 °C | 3.4 °C | 14.22 mm |
| March | -4.9 °C | 8.1 °C | 17.27 mm |
| April | -0.3 °C | 13.2 °C | 44.96 mm |
| May | 4.4 °C | 18.4 °C | 62.48 mm |
| June | 8.7 °C | 22.9 °C | 78.49 mm |
| July | 11.7 °C | 29.1 °C | 33.02 mm |
| August | 10.9 °C | 28.7 °C | 33.27 mm |
| September | 6.6 °C | 22.6 °C | 36.83 mm |
| October | 1.2 °C | 14.7 °C | 30.48 mm |
| November | -3.9 °C | 7.4 °C | 19.56 mm |
| December | -8.1 °C | 2.7 °C | 15.49 mm |
| Annual | 0.7 °C | 14.5 °C | 401.56 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 4b : -31.7°C to -28.9°C |
| Plant Hardiness Zone - 2012 | Zone 4a : -34.4°C to -31.7°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |