Gardner, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.9 °C (low) to 13.4 °C (high). Annual precipitation averages 1225.6 Millimeters. Gardner is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -11 °C | -0.6 °C | 94.23 mm |
| February | -10.3 °C | 1.1 °C | 83.82 mm |
| March | -5.9 °C | 5.4 °C | 107.44 mm |
| April | 0.3 °C | 12.7 °C | 98.04 mm |
| May | 6.3 °C | 19.1 °C | 92.46 mm |
| June | 11.4 °C | 23.8 °C | 109.73 mm |
| July | 14.6 °C | 26.7 °C | 107.19 mm |
| August | 13.4 °C | 25.9 °C | 105.16 mm |
| September | 9.3 °C | 21.8 °C | 104.14 mm |
| October | 3.1 °C | 14.6 °C | 122.94 mm |
| November | -1.9 °C | 8.2 °C | 95.5 mm |
| December | -7.1 °C | 2.4 °C | 104.9 mm |
| Annual | 1.9 °C | 13.4 °C | 1225.55 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| 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 |