Mifflin, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.9 °C (low) to 15.6 °C (high). Annual precipitation averages 1034.3 Millimeters. Mifflin is located in USDA Plant Hardiness Zone 6a. 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 | -8.2 °C | 1.1 °C | 77.98 mm |
| February | -7.4 °C | 2.7 °C | 56.13 mm |
| March | -3.1 °C | 8.2 °C | 73.15 mm |
| April | 2.8 °C | 15.8 °C | 96.27 mm |
| May | 8.7 °C | 21.4 °C | 111.76 mm |
| June | 13.9 °C | 26.4 °C | 119.63 mm |
| July | 15.7 °C | 28.2 °C | 105.41 mm |
| August | 14.8 °C | 27.6 °C | 94.74 mm |
| September | 10.6 °C | 24.3 °C | 80.52 mm |
| October | 4.6 °C | 17.4 °C | 74.93 mm |
| November | -0.6 °C | 9.9 °C | 73.15 mm |
| December | -4.9 °C | 3.7 °C | 70.61 mm |
| Annual | 3.9 °C | 15.6 °C | 1034.28 mm |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | Apr. 21 - Apr. 30 |
| 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 |