Morris Plains, New Jersey has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 5.6 °C (low) to 16.6 °C (high). Annual precipitation averages 1270.8 Millimeters. Morris Plains 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.2 °C | 3.1 °C | 96.27 mm |
| February | -5.7 °C | 4.5 °C | 70.87 mm |
| March | -1.6 °C | 9.1 °C | 107.44 mm |
| April | 4.4 °C | 16 °C | 102.62 mm |
| May | 9.8 °C | 21.6 °C | 104.39 mm |
| June | 14.9 °C | 26.4 °C | 126.24 mm |
| July | 17.7 °C | 29.6 °C | 117.35 mm |
| August | 16.8 °C | 28.4 °C | 116.59 mm |
| September | 12.7 °C | 24.7 °C | 113.79 mm |
| October | 6.2 °C | 17.9 °C | 112.01 mm |
| November | 1 °C | 11.6 °C | 91.44 mm |
| December | -2.9 °C | 5.9 °C | 111.76 mm |
| Annual | 5.6 °C | 16.6 °C | 1270.77 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |