Harrison, Maine has a Subarctic With Cool Summers And Year Around Rainfall climate (Köppen classification: Dfc). Average annual temperatures range from 1.5 °C (low) to 12.8 °C (high). Annual precipitation averages 1272 Millimeters. Harrison is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -12.7 °C | -1.8 °C | 87.88 mm |
| February | -12 °C | -0.1 °C | 88.9 mm |
| March | -6.5 °C | 4.7 °C | 99.31 mm |
| April | -0.1 °C | 12.1 °C | 106.68 mm |
| May | 6.2 °C | 19.1 °C | 91.19 mm |
| June | 11.7 °C | 23.3 °C | 121.67 mm |
| July | 14.8 °C | 26.3 °C | 107.44 mm |
| August | 13.9 °C | 25.6 °C | 104.14 mm |
| September | 9.5 °C | 21.3 °C | 100.08 mm |
| October | 3.2 °C | 14.2 °C | 139.19 mm |
| November | -2.3 °C | 7.4 °C | 111.76 mm |
| December | -8.1 °C | 1.4 °C | 113.79 mm |
| Annual | 1.5 °C | 12.8 °C | 1272.03 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfc - Subarctic With Cool Summers And Year Around Rainfall |