Allentown, New Jersey has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 7.1 °C (low) to 17.9 °C (high). Annual precipitation averages 1207.8 Millimeters. Allentown 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 | 4.9 °C | 89.92 mm |
| February | -3.6 °C | 6.3 °C | 67.06 mm |
| March | 0.2 °C | 10.6 °C | 109.98 mm |
| April | 5.8 °C | 17.2 °C | 90.17 mm |
| May | 11.1 °C | 22.5 °C | 101.09 mm |
| June | 16.2 °C | 27.7 °C | 113.54 mm |
| July | 19.2 °C | 30.1 °C | 124.71 mm |
| August | 18.3 °C | 29.2 °C | 118.11 mm |
| September | 14.3 °C | 25.7 °C | 104.14 mm |
| October | 7.9 °C | 19.1 °C | 97.54 mm |
| November | 2.3 °C | 13.3 °C | 83.31 mm |
| December | -1.7 °C | 7.6 °C | 108.2 mm |
| Annual | 7.1 °C | 17.9 °C | 1207.77 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 | Dfa - Humid Continental Hot Summers With Year Around Precipitation |