Princeton, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.1 °C (low) to 13.3 °C (high). Annual precipitation averages 1355.8 Millimeters. Princeton 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.7 °C | -0.5 °C | 105.16 mm |
| February | -9 °C | 1.1 °C | 94.74 mm |
| March | -4.6 °C | 5.3 °C | 120.9 mm |
| April | 1.6 °C | 12.6 °C | 113.79 mm |
| May | 7.2 °C | 18.8 °C | 103.38 mm |
| June | 12.6 °C | 23.5 °C | 116.33 mm |
| July | 15.7 °C | 26.4 °C | 103.89 mm |
| August | 14.7 °C | 25.6 °C | 109.47 mm |
| September | 10.9 °C | 21.5 °C | 117.09 mm |
| October | 4.6 °C | 14.6 °C | 137.67 mm |
| November | -0.9 °C | 8.3 °C | 109.47 mm |
| December | -5.9 °C | 2.6 °C | 123.95 mm |
| Annual | 3.1 °C | 13.3 °C | 1355.84 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |