Colrain, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.4 °C (low) to 12.6 °C (high). Annual precipitation averages 1386.1 Millimeters. 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 | -11.1 °C | -1.3 °C | 100.58 mm |
| February | -10.7 °C | 0.3 °C | 93.98 mm |
| March | -6.4 °C | 4.7 °C | 112.27 mm |
| April | -0.2 °C | 11.7 °C | 117.6 mm |
| May | 5.8 °C | 18.2 °C | 108.2 mm |
| June | 10.8 °C | 23.1 °C | 132.59 mm |
| July | 13.8 °C | 25.8 °C | 116.33 mm |
| August | 12.8 °C | 24.9 °C | 111.25 mm |
| September | 8.7 °C | 21.2 °C | 127.25 mm |
| October | 2.7 °C | 14 °C | 146.56 mm |
| November | -2.4 °C | 7.4 °C | 107.19 mm |
| December | -7.3 °C | 1.6 °C | 112.27 mm |
| Annual | 1.4 °C | 12.6 °C | 1386.07 mm |
| 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 : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |