Environment Canada has issued a frost warning for much of southern Ontario and some parts of the north.
The agency says temperatures are expected to fall near the freezing mark overnight.
It advises residents to cover up fruit trees and vegetable plants that could be damaged by the frost.
The advisory stretches across southern Ontario from Cornwall, all the way west to Dufferin County and north to Algonquin Provincial Park.
Parts of northeastern Ontario, including the Greater Sudbury area and North Bay, are also under the warning.
Environment Canada issues frost advisories whenever temperatures are forecast to reach 0 C during the growing season.