Williamsport, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.7 °C (low) to 16.3 °C (high). Annual precipitation averages 1100.3 Millimeters. Williamsport is located in USDA Plant Hardiness Zone 6b. 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 | -7.2 °C | 1.9 °C | 78.23 mm |
| February | -6.6 °C | 3.7 °C | 59.18 mm |
| March | -2.4 °C | 8.9 °C | 82.04 mm |
| April | 3.3 °C | 16.4 °C | 90.68 mm |
| May | 9.1 °C | 22.6 °C | 102.87 mm |
| June | 14.1 °C | 27.1 °C | 101.6 mm |
| July | 16.6 °C | 29.4 °C | 111.25 mm |
| August | 15.8 °C | 28.4 °C | 101.35 mm |
| September | 11.7 °C | 24.5 °C | 117.6 mm |
| October | 5.4 °C | 17.6 °C | 100.58 mm |
| November | 0.2 °C | 10.7 °C | 70.1 mm |
| December | -3.8 °C | 4.5 °C | 84.84 mm |
| Annual | 4.7 °C | 16.3 °C | 1100.32 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 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 | Dfa - Humid Continental Hot Summers With Year Around Precipitation |