| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F | |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F | |
| 1990 Hardiness Zone: | Zone 6a: -10F to -5F | |
| Average First Frost Date: | Oct. 1 - Oct. 10 | |
| Average Last Frost Date: | May 1 - May 10 | |
| Koppen-Geiger Climate Zone: | Dfa - Humid Continental Hot Summers | |
| Ecoregion: | 58e - Berkshire Transition | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 06791 - Harwinton, CT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 13 | 14 | 23 | 33 | 44 | 53 | 58 | 57 | 49 | 37 | 29 | 20 | 36 |
| Avg Max Temp (°F) | 33 | 36 | 45 | 57 | 69 | 77 | 82 | 80 | 72 | 61 | 49 | 38 | 58 |
| Avg Precip (In.) | 4.47 | 3.35 | 4.67 | 4.39 | 4.6 | 4.39 | 4.2 | 4.83 | 4.82 | 4.61 | 4.57 | 4.29 | 53.2 |