Pelham, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.2 °C (low) to 13.5 °C (high). Annual precipitation averages 1248.4 Millimeters. Pelham is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 21 - May 31 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -12.1 °C | -0.8 °C | 87.63 mm |
| February | -11.5 °C | 0.6 °C | 78.99 mm |
| March | -6.7 °C | 5.2 °C | 102.87 mm |
| April | -0.4 °C | 13.1 °C | 98.04 mm |
| May | 6.3 °C | 19.2 °C | 95 mm |
| June | 10.9 °C | 24.1 °C | 116.84 mm |
| July | 14 °C | 26.9 °C | 106.93 mm |
| August | 12.7 °C | 26.1 °C | 118.36 mm |
| September | 8.6 °C | 22.2 °C | 116.84 mm |
| October | 2.7 °C | 14.9 °C | 127.76 mm |
| November | -2.1 °C | 8.2 °C | 91.95 mm |
| December | -8 °C | 2.1 °C | 107.19 mm |
| Annual | 1.2 °C | 13.5 °C | 1248.4 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 21 - May 31 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |