Winchendon, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 35.5 °F (low) to 56.5 °F (high). Annual precipitation averages 49 Inches. Winchendon is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 12.1 °F | 31.2 °F | 3.71 in. |
| February | 13.5 °F | 34.2 °F | 3.24 in. |
| March | 21.5 °F | 42.0 °F | 3.99 in. |
| April | 32.8 °F | 55.1 °F | 3.85 in. |
| May | 43.7 °F | 66.7 °F | 3.74 in. |
| June | 52.9 °F | 75.3 °F | 4.55 in. |
| July | 58.4 °F | 80.5 °F | 4.34 in. |
| August | 56.6 °F | 79.0 °F | 4.29 in. |
| September | 48.9 °F | 71.6 °F | 4.25 in. |
| October | 37.7 °F | 58.5 °F | 5.04 in. |
| November | 28.5 °F | 47.0 °F | 3.76 in. |
| December | 19.1 °F | 36.5 °F | 4.22 in. |
| Annual | 35.5 °F | 56.5 °F | 48.98 in. |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -15°F to -10°F |
| Plant Hardiness Zone - 2012 | Zone 5a : -20°F to -15°F |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |