Greenwich, New Jersey has a Humid Subtropical Climate climate (Köppen classification: Cfa). Average annual temperatures range from 8.3 °C (low) to 18 °C (high). Annual precipitation averages 1136.2 Millimeters. Greenwich is located in USDA Plant Hardiness Zone 7b. The growing season typically runs from the last frost around Apr. 1 - Apr. 10 through the first frost around Nov. 1 - Nov. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -3.3 °C | 5.6 °C | 83.82 mm |
| February | -2.7 °C | 6.5 °C | 72.64 mm |
| March | 1.2 °C | 10.7 °C | 102.11 mm |
| April | 6.7 °C | 17.4 °C | 87.38 mm |
| May | 12.2 °C | 22.6 °C | 91.44 mm |
| June | 17.4 °C | 27.6 °C | 109.98 mm |
| July | 20.4 °C | 29.9 °C | 113.03 mm |
| August | 19.5 °C | 28.9 °C | 108.71 mm |
| September | 15.8 °C | 25.7 °C | 100.08 mm |
| October | 9.3 °C | 19.5 °C | 93.73 mm |
| November | 3.5 °C | 13.4 °C | 75.95 mm |
| December | -0.6 °C | 8.1 °C | 97.28 mm |
| Annual | 8.3 °C | 18 °C | 1136.15 mm |
| Average First Frost Date | Nov. 1 - Nov. 10 |
| Average Last Frost Date | Apr. 1 - Apr. 10 |
| Average Days With Frost | 75-100 Days |
| Plant Hardiness Zone | Zone 7b : -15°C to -12.2°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Cfa - Humid Subtropical Climate |