| 2023 Hardiness Zone: | Zone 6a: -10°F to -5°F Zone 5b: -15°F to -10°F |
| 2012 Hardiness Zone: | 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: | 58o - Northern Connecticut Valley |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 03603 - Charlestown, NH | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 9 | 10 | 21 | 32 | 43 | 52 | 57 | 56 | 47 | 35 | 28 | 16 | 34 |
| Avg Max Temp (°F) | 30 | 33 | 43 | 55 | 68 | 76 | 81 | 79 | 70 | 59 | 46 | 34 | 56 |
| Avg Precip (In.) | 2.92 | 2.25 | 2.84 | 2.81 | 3.6 | 3.27 | 3.72 | 3.72 | 3.1 | 3.26 | 3.06 | 2.84 | 37.36 |