You may have to cover up your outdoor plants before you go to bed Wednesday night. The National Weather Service issued a frost advisory for much of the state, including Brown, Door, Kewaunee, and Manitowoc counties, from 1 a.m. to 8 a.m. early Thursday morning. Temperatures could dip into the lower to middle 30s overnight, resulting in frost formation. Adding a layer of mulch and the combination of watering and covering your plants could help protect them from frost damage. Low temperatures are expected to be in the middle 40s to low 50s for northeast Wisconsin through the weekend.