Williamsport, Indiana has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 5.4 °C (low) to 16.5 °C (high). Annual precipitation averages 1014.7 Millimeters. Williamsport is located in USDA Plant Hardiness Zone 6a. 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 | -7.9 °C | 0.8 °C | 60.2 mm |
| February | -6.3 °C | 3.3 °C | 52.32 mm |
| March | -1.2 °C | 9.8 °C | 71.37 mm |
| April | 4.8 °C | 17 °C | 104.65 mm |
| May | 11.1 °C | 23.1 °C | 111.25 mm |
| June | 16.3 °C | 27.7 °C | 123.44 mm |
| July | 17.7 °C | 29.1 °C | 108.97 mm |
| August | 16.4 °C | 28.3 °C | 86.87 mm |
| September | 12.3 °C | 25.8 °C | 73.15 mm |
| October | 6 °C | 18.8 °C | 80.77 mm |
| November | 0.3 °C | 10.5 °C | 79.76 mm |
| December | -4.7 °C | 3.7 °C | 61.98 mm |
| Annual | 5.4 °C | 16.5 °C | 1014.73 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 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 | Dfa - Humid Continental Hot Summers With Year Around Precipitation |