South River, New Jersey has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 44.4 °F (low) to 64.2 °F (high). Annual precipitation averages 48.6 Inches. South River 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 | 23.7 °F | 40.3 °F | 3.64 in. |
| February | 25.0 °F | 43.2 °F | 2.82 in. |
| March | 31.9 °F | 51.1 °F | 4.21 in. |
| April | 41.7 °F | 63.2 °F | 3.83 in. |
| May | 51.3 °F | 73.0 °F | 4.03 in. |
| June | 60.5 °F | 81.9 °F | 4.54 in. |
| July | 66.0 °F | 86.9 °F | 4.87 in. |
| August | 64.3 °F | 84.7 °F | 4.6 in. |
| September | 57.3 °F | 78.3 °F | 4.26 in. |
| October | 45.7 °F | 66.2 °F | 4.1 in. |
| November | 35.9 °F | 55.5 °F | 3.37 in. |
| December | 28.9 °F | 45.5 °F | 4.3 in. |
| Annual | 44.4 °F | 64.2 °F | 48.57 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 |