Boyd, Montana has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 32 °F (low) to 59.4 °F (high). Annual precipitation averages 15.1 Inches. 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 | 13.9 °F | 37.0 °F | 0.55 in. |
| February | 15.4 °F | 39.7 °F | 0.58 in. |
| March | 23.0 °F | 49.7 °F | 0.85 in. |
| April | 30.3 °F | 56.9 °F | 1.9 in. |
| May | 39.3 °F | 66.0 °F | 2.97 in. |
| June | 47.1 °F | 75.7 °F | 2.2 in. |
| July | 53.0 °F | 85.7 °F | 1.03 in. |
| August | 51.0 °F | 84.7 °F | 0.91 in. |
| September | 42.5 °F | 74.2 °F | 1.32 in. |
| October | 31.9 °F | 59.3 °F | 1.53 in. |
| November | 22.4 °F | 46.5 °F | 0.71 in. |
| December | 14.6 °F | 36.9 °F | 0.58 in. |
| Annual | 32 °F | 59.4 °F | 15.13 in. |
| 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 : -20°F to -15°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |