Howland, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from -0.4 °C (low) to 12.1 °C (high). Annual precipitation averages 1152.4 Millimeters. Howland is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -15.5 °C | -3 °C | 83.31 mm |
| February | -15 °C | -1.3 °C | 71.37 mm |
| March | -8.3 °C | 3.7 °C | 82.3 mm |
| April | -1.2 °C | 10.5 °C | 95.25 mm |
| May | 4.7 °C | 17.8 °C | 89.66 mm |
| June | 9.7 °C | 22.9 °C | 118.11 mm |
| July | 13.2 °C | 26.1 °C | 88.14 mm |
| August | 12 °C | 25.9 °C | 92.46 mm |
| September | 7.6 °C | 21.4 °C | 98.04 mm |
| October | 1.5 °C | 14.1 °C | 118.87 mm |
| November | -3.2 °C | 6.8 °C | 105.92 mm |
| December | -10 °C | 0.7 °C | 108.97 mm |
| Annual | -0.4 °C | 12.1 °C | 1152.4 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |