Mifflin, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 39 °F (low) to 60 °F (high). Annual precipitation averages 40.7 Inches. 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 | 17.3 °F | 33.9 °F | 3.07 in. |
| February | 18.6 °F | 36.8 °F | 2.21 in. |
| March | 26.5 °F | 46.7 °F | 2.88 in. |
| April | 37.0 °F | 60.4 °F | 3.79 in. |
| May | 47.6 °F | 70.6 °F | 4.4 in. |
| June | 57.1 °F | 79.5 °F | 4.71 in. |
| July | 60.3 °F | 82.7 °F | 4.15 in. |
| August | 58.6 °F | 81.6 °F | 3.73 in. |
| September | 51.1 °F | 75.7 °F | 3.17 in. |
| October | 40.2 °F | 63.3 °F | 2.95 in. |
| November | 31.0 °F | 49.9 °F | 2.88 in. |
| December | 23.2 °F | 38.7 °F | 2.78 in. |
| Annual | 39 °F | 60 °F | 40.72 in. |
| 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 : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 5b : -15°F to -10°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |