Union Grove, Wisconsin has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.2 °C (low) to 13.9 °C (high). Annual precipitation averages 897.4 Millimeters. Union Grove is located in USDA Plant Hardiness Zone 5b. 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 | -10.6 °C | -1.7 °C | 44.45 mm |
| February | -9 °C | 0.4 °C | 41.4 mm |
| March | -3.8 °C | 6.4 °C | 51.31 mm |
| April | 1.8 °C | 13.4 °C | 97.79 mm |
| May | 7.8 °C | 19.8 °C | 104.14 mm |
| June | 13.5 °C | 25.3 °C | 112.78 mm |
| July | 16.2 °C | 27.8 °C | 88.39 mm |
| August | 15.2 °C | 26.9 °C | 88.39 mm |
| September | 10.9 °C | 23.3 °C | 87.38 mm |
| October | 4.5 °C | 15.9 °C | 75.69 mm |
| November | -1.4 °C | 8.1 °C | 58.67 mm |
| December | -7.1 °C | 1.3 °C | 46.99 mm |
| Annual | 3.2 °C | 13.9 °C | 897.38 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 5b : -26.1°C to -23.3°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 |