| 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: | 58e - Berkshire Transition |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 06796 - West Cornwall, CT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 12 | 14 | 23 | 33 | 44 | 53 | 57 | 56 | 48 | 37 | 29 | 19 | 35 |
| Avg Max Temp (°F) | 33 | 36 | 45 | 57 | 69 | 77 | 81 | 79 | 71 | 60 | 48 | 37 | 58 |
| Avg Precip (In.) | 3.78 | 2.96 | 3.88 | 4.05 | 4.51 | 4.27 | 4.52 | 4.58 | 4.19 | 3.99 | 4.02 | 3.77 | 48.52 |