Donegal, 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 14.7 °C (high). Annual precipitation averages 1220.5 Millimeters. Donegal is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Sep. 21 - Sep. 30.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.7 °C | 1.3 °C | 95 mm |
| February | -7 °C | 2.8 °C | 87.88 mm |
| March | -3.3 °C | 7.7 °C | 103.38 mm |
| April | 2.6 °C | 15.1 °C | 103.89 mm |
| May | 8 °C | 20.5 °C | 114.81 mm |
| June | 12.8 °C | 24.6 °C | 125.98 mm |
| July | 15.3 °C | 26.7 °C | 113.54 mm |
| August | 14.3 °C | 26.2 °C | 105.16 mm |
| September | 10.6 °C | 22.7 °C | 93.73 mm |
| October | 4.6 °C | 16.2 °C | 90.93 mm |
| November | -0.7 °C | 9.3 °C | 90.68 mm |
| December | -4.7 °C | 3.7 °C | 95.5 mm |
| Annual | 3.7 °C | 14.7 °C | 1220.48 mm |
| Average First Frost Date | Sep. 21 - Sep. 30 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°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 |