Lewistown, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.1 °C (low) to 16.6 °C (high). Annual precipitation averages 1085.3 Millimeters. Lewistown is located in USDA Plant Hardiness Zone 7a. The growing season typically runs from the last frost around Apr. 11 - Apr. 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -6.3 °C | 2.7 °C | 73.91 mm |
| February | -5.7 °C | 4.6 °C | 57.66 mm |
| March | -1.9 °C | 9.5 °C | 88.14 mm |
| April | 3.7 °C | 16.7 °C | 92.71 mm |
| May | 9.4 °C | 22.3 °C | 104.9 mm |
| June | 14.6 °C | 26.8 °C | 101.6 mm |
| July | 16.9 °C | 29.3 °C | 94.49 mm |
| August | 16.1 °C | 28.4 °C | 98.04 mm |
| September | 12.1 °C | 24.6 °C | 112.78 mm |
| October | 5.7 °C | 17.9 °C | 99.06 mm |
| November | 0.4 °C | 11.3 °C | 78.23 mm |
| December | -3.5 °C | 5.1 °C | 83.82 mm |
| Annual | 5.1 °C | 16.6 °C | 1085.34 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 11 - Apr. 20 |
| Average Days With Frost | 100-125 Days |
| Plant Hardiness Zone | Zone 7a : -17.8°C to -15°C |
| Plant Hardiness Zone - 2012 | Zone 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |