| 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 4b: -25F to -20F |
| 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 04259 - Monmouth, ME | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Annual |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Avg Min Temp (°F) | 9 | 12 | 23 | 33 | 44 | 53 | 59 | 57 | 49 | 38 | 29 | 17 | 35 |
| Avg Max Temp (°F) | 28 | 32 | 41 | 53 | 66 | 75 | 80 | 79 | 70 | 58 | 45 | 34 | 55 |
| Avg Precip (In.) | 3.78 | 2.88 | 4.2 | 4.09 | 3.92 | 3.83 | 3.65 | 3.33 | 3.63 | 4.15 | 4.29 | 3.91 | 45.67 |