Millfield, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 40.6 °F (low) to 63.8 °F (high). Annual precipitation averages 42.3 Inches. Millfield 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 | 19.8 °F | 38.8 °F | 3.25 in. |
| February | 21.1 °F | 42.2 °F | 2.76 in. |
| March | 28.3 °F | 52.0 °F | 3.72 in. |
| April | 38.8 °F | 65.9 °F | 3.79 in. |
| May | 49.3 °F | 74.3 °F | 4.19 in. |
| June | 58.4 °F | 81.9 °F | 4.34 in. |
| July | 61.8 °F | 85.0 °F | 4.37 in. |
| August | 60.7 °F | 84.3 °F | 3.33 in. |
| September | 52.4 °F | 77.6 °F | 3.39 in. |
| October | 40.0 °F | 66.4 °F | 3.0 in. |
| November | 31.4 °F | 54.3 °F | 2.98 in. |
| December | 25.4 °F | 43.4 °F | 3.18 in. |
| Annual | 40.6 °F | 63.8 °F | 42.3 in. |
| 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 : -5°F to 0°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |