Rossiter, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 3.6 °C (low) to 15 °C (high). Annual precipitation averages 1192 Millimeters. Rossiter is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 11 - May 20 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -7.8 °C | 0.9 °C | 92.96 mm |
| February | -7.3 °C | 2.8 °C | 71.12 mm |
| March | -3.6 °C | 7.7 °C | 92.71 mm |
| April | 2.2 °C | 15.5 °C | 101.6 mm |
| May | 7.9 °C | 21.2 °C | 102.62 mm |
| June | 12.8 °C | 25.2 °C | 118.62 mm |
| July | 15.1 °C | 27.3 °C | 121.92 mm |
| August | 14.3 °C | 26.7 °C | 107.7 mm |
| September | 10.6 °C | 23 °C | 107.19 mm |
| October | 4.3 °C | 16.4 °C | 87.12 mm |
| November | -0.7 °C | 9.4 °C | 92.2 mm |
| December | -4.6 °C | 3.4 °C | 96.27 mm |
| Annual | 3.6 °C | 15 °C | 1192.03 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 11 - May 20 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -23.3°C to -20.6°C |
| Plant Hardiness Zone - 2012 | Zone 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |