| 2023 Hardiness Zone: | Zone 5a: -20°F to -15°F Zone 5b: -15°F to -10°F |
| 2012 Hardiness Zone: | Zone 5a: -20°F to -15°F |
| 1990 Hardiness Zone: | Zone 5a: -20F to -15F |
| Average First Frost Date: | Oct. 1 - Oct. 10 |
| Average Last Frost Date: | May 11 - May 20 |
| Koppen-Geiger Climate Zone: | Dfb - Humid Continental Mild Summer, Wet All Year |
| Ecoregion: | 82h - Penobscot Lowlands |
| Heat Zone Days: | Rare Over 86°F |
Annual Climate Data for ZIP Code 04473 - Orono, ME | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 7 | 11 | 21 | 32 | 42 | 51 | 57 | 55 | 46 | 36 | 28 | 15 | 33 |
| Avg Max Temp (°F) | 27 | 31 | 40 | 52 | 66 | 75 | 80 | 78 | 67 | 55 | 43 | 32 | 54 |
| Avg Precip (In.) | 3.54 | 2.52 | 3.33 | 3.28 | 3.34 | 3.48 | 3.32 | 3.2 | 3.73 | 3.47 | 3.7 | 3.63 | 40.54 |