Williamsburg, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 4.8 °C (low) to 16.3 °C (high). Annual precipitation averages 1055.4 Millimeters. Williamsburg 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 | -6.6 °C | 2.5 °C | 71.37 mm |
| February | -6.2 °C | 4.2 °C | 60.2 mm |
| March | -2.4 °C | 9 °C | 80.26 mm |
| April | 3.3 °C | 16.4 °C | 86.61 mm |
| May | 9 °C | 22.1 °C | 103.38 mm |
| June | 14.2 °C | 26.4 °C | 105.66 mm |
| July | 16.5 °C | 28.9 °C | 93.73 mm |
| August | 15.7 °C | 28.2 °C | 104.39 mm |
| September | 11.8 °C | 24.3 °C | 104.9 mm |
| October | 5.4 °C | 17.7 °C | 89.92 mm |
| November | 0.3 °C | 10.9 °C | 74.93 mm |
| December | -3.7 °C | 4.8 °C | 80.01 mm |
| Annual | 4.8 °C | 16.3 °C | 1055.36 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 6b : -20.6°C to -17.8°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |