| 2023 Hardiness Zone: | Zone 7a: 0°F to 5°F | |
| 2012 Hardiness Zone: | Zone 6b: -5°F to 0°F | |
| 1990 Hardiness Zone: | Zone 6a: -10F to -5F | |
| Average First Frost Date: | Oct. 11 - Oct. 20 | |
| Average Last Frost Date: | Apr. 21 - Apr. 30 | |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year | |
| Ecoregion: | 59c - Southern New England Coastal Plains and Hills | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 06349 - Groton, CT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 19 | 21 | 29 | 38 | 47 | 56 | 62 | 62 | 54 | 43 | 34 | 25 | 41 |
| Avg Max Temp (°F) | 38 | 39 | 47 | 57 | 67 | 76 | 81 | 80 | 73 | 63 | 53 | 42 | 60 |
| Avg Precip (In.) | 4.47 | 3.59 | 4.54 | 4.33 | 3.89 | 3.67 | 3.39 | 4.43 | 4.06 | 4.1 | 4.59 | 4.39 | 49.45 |