Hampden, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.7 °C (low) to 14.9 °C (high). Annual precipitation averages 1221 Millimeters. Hampden is located in USDA Plant Hardiness Zone 6b. 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 | -8.7 °C | 1.1 °C | 87.12 mm |
| February | -8.3 °C | 2.6 °C | 77.72 mm |
| March | -3.7 °C | 7 °C | 101.85 mm |
| April | 2.2 °C | 14.4 °C | 99.82 mm |
| May | 7.8 °C | 20.5 °C | 91.95 mm |
| June | 13.1 °C | 25.1 °C | 111.51 mm |
| July | 16.2 °C | 27.9 °C | 102.87 mm |
| August | 15.2 °C | 27.1 °C | 109.22 mm |
| September | 11.1 °C | 23.1 °C | 114.81 mm |
| October | 4.7 °C | 16.3 °C | 123.44 mm |
| November | -0.6 °C | 9.9 °C | 91.95 mm |
| December | -5.1 °C | 4.2 °C | 108.71 mm |
| Annual | 3.7 °C | 14.9 °C | 1220.97 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |