According to the 2023 USDA Hardiness Zone Map Kewaunee County, Wisconsin is in Zones 5a (-20°F to -15°F), 5b (-15°F to -10°F) and 6a (-10°F to -5°F). This is a change from the 2012 USDA Hardiness Zone Map which has Kewaunee County in Zones 5a (-20°F to -15°F) and 5b (-15°F to -10°F).