West Decatur, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.1 °C (low) to 14.6 °C (high). Annual precipitation averages 1097.8 Millimeters. West Decatur 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 Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.4 °C | 0.7 °C | 77.98 mm |
| February | -8 °C | 2.4 °C | 64.26 mm |
| March | -4.2 °C | 7.3 °C | 87.12 mm |
| April | 1.8 °C | 14.9 °C | 97.03 mm |
| May | 7.6 °C | 20.8 °C | 100.84 mm |
| June | 12.3 °C | 25 °C | 112.78 mm |
| July | 14.7 °C | 27.2 °C | 102.87 mm |
| August | 13.8 °C | 26.4 °C | 98.81 mm |
| September | 9.8 °C | 22.6 °C | 103.12 mm |
| October | 3.8 °C | 15.8 °C | 93.73 mm |
| November | -1.3 °C | 9.2 °C | 76.2 mm |
| December | -5.2 °C | 3.1 °C | 83.06 mm |
| Annual | 3.1 °C | 14.6 °C | 1097.8 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| 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 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |