South Plainfield, New Jersey has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.5 °C (low) to 17.8 °C (high). Annual precipitation averages 1238.2 Millimeters. South Plainfield is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.1 °C | 4.4 °C | 91.69 mm |
| February | -4.3 °C | 6 °C | 72.64 mm |
| March | -0.5 °C | 10.5 °C | 107.19 mm |
| April | 5.1 °C | 17.3 °C | 98.55 mm |
| May | 10.5 °C | 22.8 °C | 101.6 mm |
| June | 15.6 °C | 27.7 °C | 114.55 mm |
| July | 18.6 °C | 30.4 °C | 127.51 mm |
| August | 17.7 °C | 29.3 °C | 113.54 mm |
| September | 13.7 °C | 25.6 °C | 109.98 mm |
| October | 7.3 °C | 18.9 °C | 107.95 mm |
| November | 1.8 °C | 12.9 °C | 86.11 mm |
| December | -2.1 °C | 7.3 °C | 106.93 mm |
| Annual | 6.5 °C | 17.8 °C | 1238.24 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |