Spencer, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.3 °C (low) to 14 °C (high). Annual precipitation averages 1248.9 Millimeters. Spencer is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.3 °C | 0.4 °C | 95 mm |
| February | -8.7 °C | 1.9 °C | 83.82 mm |
| March | -4.3 °C | 6.2 °C | 110.49 mm |
| April | 1.7 °C | 13.2 °C | 105.16 mm |
| May | 7.5 °C | 19.3 °C | 92.71 mm |
| June | 12.8 °C | 23.9 °C | 107.95 mm |
| July | 15.9 °C | 26.8 °C | 102.62 mm |
| August | 15 °C | 25.9 °C | 109.22 mm |
| September | 10.8 °C | 22.1 °C | 107.7 mm |
| October | 4.5 °C | 15.3 °C | 125.22 mm |
| November | -0.7 °C | 9.3 °C | 96.01 mm |
| December | -5.6 °C | 3.4 °C | 113.03 mm |
| Annual | 3.3 °C | 14 °C | 1248.93 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°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 |