| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F |
| 2012 Hardiness Zone: | Zone 5b: -15°F to -10°F |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F |
| Average First Frost Date: | Oct. 1 - Oct. 10 |
| Average Last Frost Date: | May 11 - May 20 |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year |
| Ecoregion: | 58d - Lower Berkshire Hills |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 06021 - Colebrook, CT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 11 | 13 | 21 | 32 | 44 | 52 | 57 | 56 | 48 | 37 | 29 | 18 | 35 |
| Avg Max Temp (°F) | 30 | 32 | 42 | 54 | 66 | 74 | 79 | 77 | 69 | 58 | 46 | 35 | 55 |
| Avg Precip (In.) | 4.41 | 3.51 | 5.04 | 4.5 | 4.85 | 4.55 | 4.75 | 4.79 | 4.88 | 4.99 | 4.68 | 4.34 | 55.29 |