Witmer, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 6.4 °C (low) to 17.3 °C (high). Annual precipitation averages 1165.9 Millimeters. Witmer 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. 21 - Oct. 31.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -5.2 °C | 3.9 °C | 82.3 mm |
| February | -4.7 °C | 5.3 °C | 66.29 mm |
| March | -0.7 °C | 10.3 °C | 97.03 mm |
| April | 4.9 °C | 17.4 °C | 92.46 mm |
| May | 10.6 °C | 22.6 °C | 96.52 mm |
| June | 15.8 °C | 27.4 °C | 111 mm |
| July | 18.4 °C | 29.7 °C | 113.03 mm |
| August | 17.5 °C | 28.8 °C | 99.82 mm |
| September | 13.6 °C | 25.1 °C | 121.41 mm |
| October | 7.2 °C | 18.6 °C | 112.01 mm |
| November | 1.6 °C | 12.2 °C | 81.53 mm |
| December | -2.5 °C | 6.4 °C | 92.46 mm |
| Annual | 6.4 °C | 17.3 °C | 1165.86 mm |
| Average First Frost Date | Oct. 21 - Oct. 31 |
| 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 | Abnormally Dry |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |