South Hadley, Massachusetts has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.8 °C (low) to 15.4 °C (high). Annual precipitation averages 1182.7 Millimeters. South Hadley is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9 °C | 1.2 °C | 83.82 mm |
| February | -8.3 °C | 2.8 °C | 73.41 mm |
| March | -3.4 °C | 7.4 °C | 92.46 mm |
| April | 2.5 °C | 14.9 °C | 95.76 mm |
| May | 8.3 °C | 21.2 °C | 92.71 mm |
| June | 13.4 °C | 25.8 °C | 111.51 mm |
| July | 16.4 °C | 28.8 °C | 100.84 mm |
| August | 15.5 °C | 27.8 °C | 107.7 mm |
| September | 11.2 °C | 23.8 °C | 114.81 mm |
| October | 4.8 °C | 16.8 °C | 121.67 mm |
| November | -0.6 °C | 10.1 °C | 85.6 mm |
| December | -5.3 °C | 4.2 °C | 102.36 mm |
| Annual | 3.8 °C | 15.4 °C | 1182.65 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| 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 |