Colebrook, Connecticut has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 37.2 °F (low) to 56.9 °F (high). Annual precipitation averages 52.6 Inches. Colebrook is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 15.0 °F | 32.2 °F | 3.69 in. |
| February | 16.3 °F | 34.8 °F | 3.29 in. |
| March | 23.9 °F | 43.0 °F | 4.24 in. |
| April | 34.3 °F | 56.3 °F | 4.02 in. |
| May | 45.0 °F | 67.4 °F | 4.24 in. |
| June | 54.0 °F | 75.3 °F | 4.86 in. |
| July | 58.8 °F | 80.1 °F | 4.67 in. |
| August | 56.9 °F | 78.5 °F | 4.58 in. |
| September | 49.9 °F | 71.3 °F | 4.94 in. |
| October | 39.9 °F | 59.3 °F | 5.44 in. |
| November | 30.3 °F | 47.2 °F | 4.0 in. |
| December | 21.6 °F | 37.4 °F | 4.62 in. |
| Annual | 37.2 °F | 56.9 °F | 52.59 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |