Port Allegany, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.8 °C (low) to 13.9 °C (high). Annual precipitation averages 1078.5 Millimeters. Port Allegany is located in USDA Plant Hardiness Zone 5b. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.7 °C | -0.2 °C | 77.72 mm |
| February | -9.3 °C | 1.3 °C | 57.4 mm |
| March | -5.7 °C | 6.3 °C | 75.44 mm |
| April | 0 °C | 13.8 °C | 90.93 mm |
| May | 5.9 °C | 20.5 °C | 96.77 mm |
| June | 10.8 °C | 24.4 °C | 107.7 mm |
| July | 13.2 °C | 26.4 °C | 109.47 mm |
| August | 12.8 °C | 25.7 °C | 102.36 mm |
| September | 8.9 °C | 22.1 °C | 96.01 mm |
| October | 2.8 °C | 15.3 °C | 101.6 mm |
| November | -1.9 °C | 8.3 °C | 82.8 mm |
| December | -5.9 °C | 2.4 °C | 80.26 mm |
| Annual | 1.8 °C | 13.9 °C | 1078.46 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5b : -26.1°C to -23.3°C |
| Plant Hardiness Zone - 2012 | Zone 5a : -28.9°C to -26.1°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |