Island Falls, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 30.6 °F (low) to 52 °F (high). Annual precipitation averages 45.9 Inches. Island Falls is located in USDA Plant Hardiness Zone 4b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Sep.11 - Sep. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 2.5 °F | 23.7 °F | 3.54 in. |
| February | 3.8 °F | 26.8 °F | 2.81 in. |
| March | 15.4 °F | 36.5 °F | 3.48 in. |
| April | 28.8 °F | 49.5 °F | 3.59 in. |
| May | 40.0 °F | 63.6 °F | 3.89 in. |
| June | 49.5 °F | 72.9 °F | 4.35 in. |
| July | 55.5 °F | 77.8 °F | 3.87 in. |
| August | 53.3 °F | 76.8 °F | 3.69 in. |
| September | 45.5 °F | 68.9 °F | 3.64 in. |
| October | 35.0 °F | 55.0 °F | 4.7 in. |
| November | 25.6 °F | 41.9 °F | 4.08 in. |
| December | 12.5 °F | 30.2 °F | 4.23 in. |
| Annual | 30.6 °F | 52 °F | 45.87 in. |
| Average First Frost Date | Sep.11 - Sep. 20 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | Over 180 Days |
| Plant Hardiness Zone | Zone 4b : -25°F to -20°F |
| Plant Hardiness Zone - 2012 | Zone 4b : -25°F to -20°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |