Mifflinville, Pennsylvania has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 5 °C (low) to 16.8 °C (high). Annual precipitation averages 1113.5 Millimeters. Mifflinville is located in USDA Plant Hardiness Zone 6b. 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 | 74.68 mm |
| February | -5.8 °C | 4.1 °C | 58.42 mm |
| March | -1.9 °C | 9.3 °C | 77.98 mm |
| April | 3.6 °C | 17.1 °C | 97.28 mm |
| May | 9.3 °C | 23 °C | 97.54 mm |
| June | 14.4 °C | 27.4 °C | 117.35 mm |
| July | 16.9 °C | 29.9 °C | 113.79 mm |
| August | 16 °C | 28.9 °C | 104.14 mm |
| September | 11.9 °C | 25.1 °C | 121.16 mm |
| October | 5.6 °C | 18.2 °C | 96.52 mm |
| November | 0.6 °C | 11.1 °C | 75.18 mm |
| December | -3.6 °C | 5.2 °C | 79.5 mm |
| Annual | 5 °C | 16.8 °C | 1113.54 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 6b : -20.6°C to -17.8°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 |