Mill Creek, Pennsylvania has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.5 °C (low) to 16.8 °C (high). Annual precipitation averages 1029.5 Millimeters. Mill Creek 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 | -6.7 °C | 2.8 °C | 70.87 mm |
| February | -6.2 °C | 4.6 °C | 59.18 mm |
| March | -2.4 °C | 9.3 °C | 85.85 mm |
| April | 3 °C | 17 °C | 90.93 mm |
| May | 8.8 °C | 22.7 °C | 99.31 mm |
| June | 13.9 °C | 27.1 °C | 101.35 mm |
| July | 16.2 °C | 29.6 °C | 83.57 mm |
| August | 15.4 °C | 28.7 °C | 89.41 mm |
| September | 11.4 °C | 24.8 °C | 101.85 mm |
| October | 5.1 °C | 18.2 °C | 93.22 mm |
| November | -0.1 °C | 11.5 °C | 73.66 mm |
| December | -3.9 °C | 5.2 °C | 80.26 mm |
| Annual | 4.5 °C | 16.8 °C | 1029.46 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 | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |