Williams Bay, Wisconsin has a Humid Continental Hot Summers With Year Around Precipitation climate (Köppen classification: Dfa). Average annual temperatures range from 3.3 °C (low) to 14.2 °C (high). Annual precipitation averages 968.5 Millimeters. Williams Bay is located in USDA Plant Hardiness Zone 5b. 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 | -10.4 °C | -1.8 °C | 46.23 mm |
| February | -8.9 °C | 0.4 °C | 45.47 mm |
| March | -3.7 °C | 6.8 °C | 55.88 mm |
| April | 2 °C | 14.1 °C | 95.76 mm |
| May | 8.5 °C | 20.6 °C | 110.24 mm |
| June | 13.8 °C | 25.9 °C | 139.95 mm |
| July | 16.2 °C | 28.1 °C | 92.46 mm |
| August | 15.2 °C | 27.2 °C | 103.38 mm |
| September | 10.8 °C | 23.6 °C | 91.69 mm |
| October | 4.6 °C | 16.2 °C | 75.44 mm |
| November | -1.4 °C | 8 °C | 60.2 mm |
| December | -7.2 °C | 1.1 °C | 51.82 mm |
| Annual | 3.3 °C | 14.2 °C | 968.52 mm |
| Average First Frost Date | Oct. 1 - Oct. 10 |
| Average Last Frost Date | May 1 - May 10 |
| 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 |