According to the 2023 USDA Hardiness Zone Map Sheridan County, Montana is in Zones 3a (-40°F to -35°F), 3b (-35°F to -30°F) and 4a (-30°F to -25°F). There is no change from the 2012 USDA Hardiness Zone Map which has Sheridan County in also in Zones 3a (-40°F to -35°F), 3b (-35°F to -30°F) and 4a (-30°F to -25°F).