Mercerville, New Jersey has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 7.2 °C (low) to 17.8 °C (high). Annual precipitation averages 1215.7 Millimeters. Mercerville 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 | -4.4 °C | 4.7 °C | 89.66 mm |
| February | -3.6 °C | 6.2 °C | 67.82 mm |
| March | 0.2 °C | 10.6 °C | 110.24 mm |
| April | 5.8 °C | 17.2 °C | 90.42 mm |
| May | 11.2 °C | 22.6 °C | 102.87 mm |
| June | 16.3 °C | 27.6 °C | 114.05 mm |
| July | 19.3 °C | 30.2 °C | 128.27 mm |
| August | 18.3 °C | 29.2 °C | 114.81 mm |
| September | 14.3 °C | 25.7 °C | 103.38 mm |
| October | 7.9 °C | 19 °C | 99.57 mm |
| November | 2.3 °C | 13.1 °C | 84.84 mm |
| December | -1.7 °C | 7.4 °C | 109.73 mm |
| Annual | 7.2 °C | 17.8 °C | 1215.66 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 | Moderate Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |