For the second time this week, Environment Canada has issued a frost advisory for Windsor-Essex, Chatham-Kent, and Elgin County.
Temperatures are expected to drop below the freezing mark Wednesday night, causing the frost to develop.
"Frost may damage some crops in frost-prone areas," the national weather agency said.
Residents in the affected areas are advised to cover up any outdoor plants.
Frost advisories are issued when temperatures are expected to reach the freezing mark during the growing season, potentially causing damage and destruction to plants and crops.
Any frost that does form overnight will melt away after sunrise when temperatures begin to rise. Environment Canada is calling for sunshine and a daytime high of 10 C on Thursday.