Viola, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.2 °C (low) to 13.6 °C (high). Annual precipitation averages 977.1 Millimeters. Viola is located in USDA Plant Hardiness Zone 5a. The growing season typically runs from the last frost around May 1 - May 10 through the first frost around Oct. 1 - Oct. 10.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -13.2 °C | -3.1 °C | 31.24 mm |
| February | -11.4 °C | -0.5 °C | 30.73 mm |
| March | -5.1 °C | 6.3 °C | 50.55 mm |
| April | 1.6 °C | 13.9 °C | 101.85 mm |
| May | 8 °C | 20.6 °C | 121.92 mm |
| June | 13.8 °C | 25.9 °C | 141.99 mm |
| July | 16.1 °C | 27.9 °C | 120.4 mm |
| August | 14.9 °C | 26.9 °C | 113.79 mm |
| September | 10.1 °C | 22.8 °C | 103.38 mm |
| October | 3.3 °C | 15.7 °C | 69.85 mm |
| November | -3 °C | 7 °C | 51.31 mm |
| December | -9.3 °C | -0.2 °C | 40.13 mm |
| Annual | 2.2 °C | 13.6 °C | 977.14 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| Average Days With Frost | 150-180 Days |
| Plant Hardiness Zone | Zone 5a : -28.9°C to -26.1°C |
| Plant Hardiness Zone - 2012 | Zone 4b : -31.7°C to -28.9°C |
| Current Drought Conditions | Normal |
| Köppen Climate Classification | Dfb - Humid Continental Mild Summer, Wet All Year |