Sister Bay, Wisconsin has a Humid Continental Mild Summer, Wet All Year climate (Köppen classification: Dfb). Average annual temperatures range from 2.8 °C (low) to 11.4 °C (high). Annual precipitation averages 783.6 Millimeters. Sister 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. 11 - Oct. 20.
| Month | Avg. Low | Avg. High | Avg. Precip |
|---|---|---|---|
| January | -10.7 °C | -3.3 °C | 44.7 mm |
| February | -10.5 °C | -2 °C | 25.4 mm |
| March | -5.6 °C | 3.3 °C | 42.42 mm |
| April | 0.3 °C | 9.6 °C | 71.12 mm |
| May | 6.4 °C | 16.7 °C | 87.38 mm |
| June | 12.2 °C | 22.3 °C | 84.33 mm |
| July | 15.3 °C | 25.2 °C | 74.68 mm |
| August | 15.4 °C | 24.6 °C | 80.77 mm |
| September | 11.3 °C | 20.3 °C | 85.34 mm |
| October | 5.6 °C | 13.3 °C | 86.61 mm |
| November | -0.3 °C | 6.1 °C | 58.17 mm |
| December | -6.1 °C | 0.1 °C | 42.67 mm |
| Annual | 2.8 °C | 11.4 °C | 783.59 mm |
| 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 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 | Dfb - Humid Continental Mild Summer, Wet All Year |