Boyd, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Annual precipitation averages 384.3 Millimeters. Boyd 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.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.1 °C | 2.8 °C | 13.97 mm |
| February | -9.2 °C | 4.3 °C | 14.73 mm |
| March | -5 °C | 9.8 °C | 21.59 mm |
| April | -0.9 °C | 13.8 °C | 48.26 mm |
| May | 4.1 °C | 18.9 °C | 75.44 mm |
| June | 8.4 °C | 24.3 °C | 55.88 mm |
| July | 11.7 °C | 29.8 °C | 26.16 mm |
| August | 10.6 °C | 29.3 °C | 23.11 mm |
| September | 5.8 °C | 23.4 °C | 33.53 mm |
| October | -0.1 °C | 15.2 °C | 38.86 mm |
| November | -5.3 °C | 8.1 °C | 18.03 mm |
| December | -9.7 °C | 2.7 °C | 14.73 mm |
| Annual | 0 °C | 15.2 °C | 384.29 mm |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | Over 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 | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |