Derry, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.6 °C (low) to 16 °C (high). Annual precipitation averages 1271.5 Millimeters. Derry is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.7 °C | 2.5 °C | 100.33 mm |
| February | -6.1 °C | 4.2 °C | 80.52 mm |
| March | -2.2 °C | 9.1 °C | 99.57 mm |
| April | 3.4 °C | 16.4 °C | 108.97 mm |
| May | 9.1 °C | 21.8 °C | 121.41 mm |
| June | 13.8 °C | 25.9 °C | 129.54 mm |
| July | 16.1 °C | 27.9 °C | 133.6 mm |
| August | 15.2 °C | 27.4 °C | 102.87 mm |
| September | 11.4 °C | 23.9 °C | 112.52 mm |
| October | 5.1 °C | 17.3 °C | 89.41 mm |
| November | -0.1 °C | 10.7 °C | 95.25 mm |
| December | -3.8 °C | 4.9 °C | 97.54 mm |
| Annual | 4.6 °C | 16 °C | 1271.53 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |