According to the 2023 USDA Hardiness Zone Map Ashland County, Wisconsin is in Zones 4a (-30°F to -25°F), 4b (-25°F to -20°F), 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 Ashland County in Zones 3b (-35°F to -30°F), 4a (-30°F to -25°F), 4b (-25°F to -20°F) and 5a (-20°F to -15°F).