| 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 | |
| 1990 Hardiness Zone: | Zone 1b: -15F to -10F | |
| 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 01863 - North Chelmsford, MA | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 14 | 17 | 25 | 35 | 45 | 54 | 60 | 58 | 50 | 38 | 30 | 21 | 37 |
| Avg Max Temp (°F) | 34 | 37 | 46 | 58 | 70 | 78 | 84 | 82 | 73 | 62 | 50 | 38 | 59 |
| Avg Precip (In.) | 3.89 | 2.99 | 3.64 | 3.92 | 3.44 | 3.66 | 3.32 | 3.34 | 3.69 | 3.98 | 4.35 | 3.76 | 43.99 |