Union Dale, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 1.8 °C (low) to 12.6 °C (high). Annual precipitation averages 1213.1 Millimeters. Union Dale is located in USDA Plant Hardiness Zone 5b. 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 | -10.5 °C | -1.3 °C | 89.15 mm |
| February | -10.1 °C | 0.2 °C | 69.6 mm |
| March | -5.9 °C | 4.8 °C | 84.58 mm |
| April | 0.3 °C | 12.2 °C | 101.6 mm |
| May | 6.4 °C | 18.6 °C | 116.33 mm |
| June | 11.6 °C | 23.1 °C | 132.08 mm |
| July | 13.8 °C | 25.5 °C | 116.33 mm |
| August | 13.1 °C | 24.6 °C | 100.33 mm |
| September | 9 °C | 20.8 °C | 111.51 mm |
| October | 2.9 °C | 14.1 °C | 118.36 mm |
| November | -2.1 °C | 7.4 °C | 80.26 mm |
| December | -6.6 °C | 1.5 °C | 92.96 mm |
| Annual | 1.8 °C | 12.6 °C | 1213.09 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 5b : -26.1°C to -23.3°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 |