| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F | |
| 2012 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5a: -20°F to -15°F Zone 5b: -15°F to -10°F | |
| 1990 Hardiness Zone: | Zone 5a: -20F to -15F | |
| Average First Frost Date: | Sep. 21 - Sep. 30 | |
| Average Last Frost Date: | Jun. 1 - Jun. 10 | |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year | |
| Ecoregion: | 58g - Worcester/Monadnock Plateau | |
| Current Drought Status: | Exceptional Drought | |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 03455 - Marlborough, NH | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 8 | 10 | 20 | 31 | 42 | 51 | 55 | 54 | 45 | 34 | 26 | 15 | 33 |
| Avg Max Temp (°F) | 30 | 33 | 42 | 54 | 67 | 75 | 80 | 78 | 69 | 58 | 46 | 34 | 55 |
| Avg Precip (In.) | 3.51 | 2.61 | 3.42 | 3.42 | 4.03 | 3.79 | 3.95 | 3.96 | 3.51 | 3.71 | 3.62 | 3.34 | 42.88 |