Mountain Lakes, New Jersey has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 42.1 °F (low) to 61.7 °F (high). Annual precipitation averages 49.6 Inches. Mountain Lakes is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 20.6 °F | 37.5 °F | 3.73 in. |
| February | 21.6 °F | 39.9 °F | 2.77 in. |
| March | 29.1 °F | 48.1 °F | 4.13 in. |
| April | 39.9 °F | 60.6 °F | 3.99 in. |
| May | 49.5 °F | 70.7 °F | 4.06 in. |
| June | 59.1 °F | 79.4 °F | 5.09 in. |
| July | 63.9 °F | 85.3 °F | 4.42 in. |
| August | 62.5 °F | 83.2 °F | 4.64 in. |
| September | 54.9 °F | 76.4 °F | 4.4 in. |
| October | 43.4 °F | 64.4 °F | 4.41 in. |
| November | 34.1 °F | 52.8 °F | 3.62 in. |
| December | 26.7 °F | 42.4 °F | 4.33 in. |
| Annual | 42.1 °F | 61.7 °F | 49.59 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| 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 | Moderate Drought |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |