Hampden, Maine has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.3 °C (low) to 12.6 °C (high). Annual precipitation averages 1209 Millimeters. Hampden is located in USDA Plant Hardiness Zone 5a. 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 | -13.2 °C | -2.2 °C | 92.71 mm |
| February | -12.2 °C | -0.4 °C | 84.58 mm |
| March | -6.2 °C | 4.2 °C | 107.95 mm |
| April | 0 °C | 11.2 °C | 109.47 mm |
| May | 5.8 °C | 18.1 °C | 92.2 mm |
| June | 10.9 °C | 23.2 °C | 101.6 mm |
| July | 14.5 °C | 26.3 °C | 82.8 mm |
| August | 13.5 °C | 25.8 °C | 85.34 mm |
| September | 9.2 °C | 21.4 °C | 98.81 mm |
| October | 3.2 °C | 14.2 °C | 124.21 mm |
| November | -1.9 °C | 7.6 °C | 105.41 mm |
| December | -8.3 °C | 1.3 °C | 123.95 mm |
| Annual | 1.3 °C | 12.6 °C | 1209.03 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 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Abnormally Dry |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |