Stewartstown, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.6 °C (low) to 17.4 °C (high). Annual precipitation averages 1215.7 Millimeters. Stewartstown is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 21 - Apr. 30 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -4.7 °C | 4.2 °C | 88.39 mm |
| February | -3.9 °C | 6.1 °C | 71.88 mm |
| March | -0.3 °C | 10.9 °C | 105.16 mm |
| April | 5.4 °C | 17.8 °C | 97.03 mm |
| May | 10.7 °C | 22.7 °C | 102.62 mm |
| June | 15.7 °C | 27 °C | 104.39 mm |
| July | 18.2 °C | 29.4 °C | 118.11 mm |
| August | 17.2 °C | 28.5 °C | 106.43 mm |
| September | 13.6 °C | 24.9 °C | 127.76 mm |
| October | 7.3 °C | 18.7 °C | 110.24 mm |
| November | 2.1 °C | 12.4 °C | 86.87 mm |
| December | -2.1 °C | 6.6 °C | 96.77 mm |
| Annual | 6.6 °C | 17.4 °C | 1215.65 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 7a : -17.8°C to -15°C |
| Current Drought Conditions | Severe Drought |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |