Unionville, Michigan has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 38.2 °F (low) to 56.1 °F (high). Annual precipitation averages 31 Inches. Unionville is located in USDA Plant Hardiness Zone 6a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | 15.7 °F | 29.0 °F | 1.69 in. |
| February | 15.8 °F | 31.6 °F | 1.54 in. |
| March | 24.0 °F | 41.1 °F | 1.61 in. |
| April | 35.0 °F | 54.7 °F | 3.24 in. |
| May | 46.6 °F | 67.2 °F | 3.29 in. |
| June | 56.5 °F | 76.9 °F | 3.4 in. |
| July | 60.0 °F | 80.9 °F | 3.1 in. |
| August | 58.5 °F | 78.8 °F | 3.23 in. |
| September | 51.5 °F | 72.8 °F | 2.89 in. |
| October | 41.0 °F | 59.7 °F | 2.93 in. |
| November | 31.5 °F | 45.9 °F | 2.31 in. |
| December | 22.8 °F | 34.5 °F | 1.78 in. |
| Annual | 38.2 °F | 56.1 °F | 31.01 in. |
| Average First Frost Date | Oct. 11 - Oct. 20 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 125-150 Days |
| Plant Hardiness Zone | Zone 6a : -10°F to -5°F |
| Plant Hardiness Zone - 2012 | Zone 6a : -10°F to -5°F |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |