| 2023 Hardiness Zone: | Zone 6b: -5°F to 0°F | |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F 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: | May 1 - May 10 | |
| 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 06447 - Marlborough, CT | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 16 | 18 | 26 | 36 | 45 | 55 | 60 | 59 | 50 | 38 | 31 | 22 | 38 |
| Avg Max Temp (°F) | 35 | 38 | 46 | 58 | 69 | 77 | 82 | 80 | 72 | 62 | 51 | 40 | 59 |
| Avg Precip (In.) | 4.39 | 3.16 | 4.34 | 4.44 | 4.28 | 4.21 | 4.14 | 4.34 | 4.4 | 4.63 | 4.57 | 4.07 | 50.96 |