Heilwood, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.7 °C (low) to 14.5 °C (high). Annual precipitation averages 1243.3 Millimeters. Heilwood is located in USDA Plant Hardiness Zone 6a. 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 | -7.8 °C | 0.8 °C | 100.08 mm |
| February | -7.3 °C | 2.5 °C | 77.47 mm |
| March | -3.6 °C | 7.4 °C | 100.08 mm |
| April | 2.4 °C | 14.9 °C | 105.16 mm |
| May | 8.3 °C | 20.5 °C | 107.19 mm |
| June | 13 °C | 24.6 °C | 116.33 mm |
| July | 15.3 °C | 26.7 °C | 129.54 mm |
| August | 14.4 °C | 25.9 °C | 110.49 mm |
| September | 10.8 °C | 22.4 °C | 109.22 mm |
| October | 4.7 °C | 16 °C | 90.17 mm |
| November | -0.8 °C | 9.2 °C | 98.04 mm |
| December | -4.8 °C | 3.2 °C | 99.57 mm |
| Annual | 3.7 °C | 14.5 °C | 1243.34 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |