| 2023 Hardiness Zone: | 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: | Oct. 11 - Oct. 20 |
| Average Last Frost Date: | May 11 - May 20 |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year |
| Ecoregion: | 82e - Central Maine Embayment |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 04348 - Jefferson, ME | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 10 | 13 | 23 | 33 | 44 | 53 | 58 | 57 | 49 | 38 | 30 | 17 | 35 |
| Avg Max Temp (°F) | 29 | 32 | 41 | 53 | 65 | 73 | 79 | 77 | 69 | 57 | 46 | 35 | 55 |
| Avg Precip (In.) | 4.06 | 3.09 | 4.24 | 4.15 | 3.9 | 3.66 | 3.29 | 2.97 | 3.77 | 4.11 | 4.55 | 4.22 | 46 |