Colrain, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 34.5 °F (low) to 54.7 °F (high). Annual precipitation averages 54.6 Inches. Colrain is located in USDA Plant Hardiness Zone 5b. 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 | 12.0 °F | 29.7 °F | 3.96 in. |
| February | 12.7 °F | 32.6 °F | 3.7 in. |
| March | 20.5 °F | 40.4 °F | 4.42 in. |
| April | 31.7 °F | 53.0 °F | 4.63 in. |
| May | 42.4 °F | 64.7 °F | 4.26 in. |
| June | 51.5 °F | 73.6 °F | 5.22 in. |
| July | 56.9 °F | 78.4 °F | 4.58 in. |
| August | 55.1 °F | 76.9 °F | 4.38 in. |
| September | 47.7 °F | 70.1 °F | 5.01 in. |
| October | 36.9 °F | 57.2 °F | 5.77 in. |
| November | 27.7 °F | 45.3 °F | 4.22 in. |
| December | 18.8 °F | 34.8 °F | 4.42 in. |
| Annual | 34.5 °F | 54.7 °F | 54.57 in. |
| 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 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |