Prompton, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.7 °C (low) to 14.2 °C (high). Annual precipitation averages 1194.6 Millimeters. Prompton 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 | 0.1 °C | 89.15 mm |
| February | -9.4 °C | 1.6 °C | 70.1 mm |
| March | -4.9 °C | 6.4 °C | 87.12 mm |
| April | 0.9 °C | 13.9 °C | 99.57 mm |
| May | 7.3 °C | 20.3 °C | 102.62 mm |
| June | 12.6 °C | 24.6 °C | 124.97 mm |
| July | 15 °C | 27.1 °C | 110.49 mm |
| August | 14.2 °C | 26.1 °C | 101.35 mm |
| September | 10.1 °C | 22.4 °C | 115.06 mm |
| October | 3.6 °C | 15.7 °C | 114.3 mm |
| November | -1.6 °C | 9.1 °C | 79.25 mm |
| December | -6.1 °C | 2.8 °C | 100.58 mm |
| Annual | 2.7 °C | 14.2 °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 |