Environment Canada has issued a frost advisory for Barrie, Collingwood, Hillsdale, Midland, Coldwater, Orr Lake, Orillia, Lagoon City and Washago, Ont.
The federal weather agency says patchy frost is expected overnight into Tuesday morning as temperatures drop to near or just below the freezing mark.
Environment Canada says plants may be damaged or destroyed by the frost and to cover them up.
The daily email you need for
Barrie's top news stories.
Frost advisories are issued when temperatures are expected to reach the freezing mark during the growing season, leading to the potential damage or destruction of crops and plants.