Bethany, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.5 °C (low) to 13.7 °C (high). Annual precipitation averages 1194.6 Millimeters. Bethany 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. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -9.9 °C | -0.3 °C | 89.66 mm |
| February | -9.4 °C | 1.2 °C | 68.83 mm |
| March | -5.1 °C | 5.9 °C | 85.6 mm |
| April | 0.8 °C | 13.3 °C | 98.04 mm |
| May | 7.2 °C | 19.7 °C | 103.63 mm |
| June | 12.3 °C | 24.1 °C | 125.73 mm |
| July | 14.7 °C | 26.5 °C | 112.27 mm |
| August | 14 °C | 25.6 °C | 101.09 mm |
| September | 10 °C | 21.8 °C | 115.57 mm |
| October | 3.6 °C | 15.1 °C | 112.27 mm |
| November | -1.6 °C | 8.6 °C | 80.52 mm |
| December | -6.1 °C | 2.4 °C | 101.35 mm |
| Annual | 2.5 °C | 13.7 °C | 1194.56 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 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 | Dfb - Humid Continental Mild Summer, Wet All Year |