Stonerstown, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 4.2 °C (low) to 16.8 °C (high). Annual precipitation averages 1035.6 Millimeters. Stonerstown is located in USDA Plant Hardiness Zone 6b. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7 °C | 3 °C | 73.15 mm |
| February | -6.3 °C | 4.8 °C | 58.93 mm |
| March | -2.7 °C | 9.6 °C | 88.65 mm |
| April | 2.8 °C | 16.9 °C | 90.93 mm |
| May | 8.5 °C | 22.4 °C | 101.09 mm |
| June | 13.4 °C | 26.9 °C | 93.47 mm |
| July | 15.9 °C | 29.4 °C | 99.57 mm |
| August | 14.9 °C | 28.5 °C | 86.87 mm |
| September | 10.9 °C | 24.7 °C | 99.57 mm |
| October | 4.5 °C | 18.2 °C | 83.57 mm |
| November | -0.7 °C | 11.4 °C | 79.25 mm |
| December | -4.3 °C | 5.3 °C | 80.52 mm |
| Annual | 4.2 °C | 16.8 °C | 1035.57 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 6b : -20.6°C to -17.8°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |