South Plainfield, New Jersey has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 43.7 °F (low) to 64 °F (high). Annual precipitation averages 48.8 Inches. 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 | 22.9 °F | 40.0 °F | 3.61 in. |
| February | 24.2 °F | 42.8 °F | 2.86 in. |
| March | 31.1 °F | 50.9 °F | 4.22 in. |
| April | 41.2 °F | 63.2 °F | 3.88 in. |
| May | 50.9 °F | 73.0 °F | 4.0 in. |
| June | 60.1 °F | 81.9 °F | 4.51 in. |
| July | 65.4 °F | 86.8 °F | 5.02 in. |
| August | 63.9 °F | 84.8 °F | 4.47 in. |
| September | 56.7 °F | 78.1 °F | 4.33 in. |
| October | 45.1 °F | 66.1 °F | 4.25 in. |
| November | 35.2 °F | 55.3 °F | 3.39 in. |
| December | 28.2 °F | 45.1 °F | 4.21 in. |
| Annual | 43.7 °F | 64 °F | 48.75 in. |
| 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 : 0°F to 5°F |
| Plant Hardiness Zone - 2012 | Zone 6b : -5°F to 0°F |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |