Lilly, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3 °C (low) to 14.1 °C (high). Annual precipitation averages 1178.1 Millimeters. Lilly 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. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -8.3 °C | 0.5 °C | 84.84 mm |
| February | -7.9 °C | 2.1 °C | 74.93 mm |
| March | -4.2 °C | 6.8 °C | 96.52 mm |
| April | 1.6 °C | 14.6 °C | 101.35 mm |
| May | 7.4 °C | 19.9 °C | 110.24 mm |
| June | 12.2 °C | 24.3 °C | 107.7 mm |
| July | 14.4 °C | 26.3 °C | 113.54 mm |
| August | 13.6 °C | 25.6 °C | 107.7 mm |
| September | 9.9 °C | 22.1 °C | 109.22 mm |
| October | 3.9 °C | 15.6 °C | 92.2 mm |
| November | -1.6 °C | 8.7 °C | 81.79 mm |
| December | -5.4 °C | 2.8 °C | 98.04 mm |
| Annual | 3 °C | 14.1 °C | 1178.07 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| 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 5b : -26.1°C to -23.3°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |