| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 6b: -5°F to 0°F | |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F 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: | 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 01450 - Groton, MA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 13 | 17 | 25 | 34 | 45 | 53 | 59 | 57 | 49 | 37 | 30 | 20 | 36 |
| Avg Max Temp (°F) | 34 | 37 | 46 | 58 | 70 | 78 | 84 | 82 | 73 | 62 | 50 | 38 | 59 |
| Avg Precip (In.) | 4 | 3.13 | 3.97 | 3.97 | 3.63 | 3.75 | 3.58 | 3.66 | 3.77 | 4.09 | 4.32 | 3.86 | 45.73 |