Millfield, Ohio has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 4.8 °C (low) to 17.7 °C (high). Annual precipitation averages 1074.4 Millimeters. 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 | -6.8 °C | 3.8 °C | 82.55 mm |
| February | -6.1 °C | 5.7 °C | 70.1 mm |
| March | -2.1 °C | 11.1 °C | 94.49 mm |
| April | 3.8 °C | 18.8 °C | 96.27 mm |
| May | 9.6 °C | 23.5 °C | 106.43 mm |
| June | 14.7 °C | 27.7 °C | 110.24 mm |
| July | 16.6 °C | 29.4 °C | 111 mm |
| August | 15.9 °C | 29.1 °C | 84.58 mm |
| September | 11.3 °C | 25.3 °C | 86.11 mm |
| October | 4.4 °C | 19.1 °C | 76.2 mm |
| November | -0.3 °C | 12.4 °C | 75.69 mm |
| December | -3.7 °C | 6.3 °C | 80.77 mm |
| Annual | 4.8 °C | 17.7 °C | 1074.43 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 6a : -23.3°C to -20.6°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfa - Humid Continental Hot Summers With Year Around Precipitation |