Environment Canada has issued a winter weather travel advisory for northern Wellington County, Ont., including Mount Forest and Arthur.
The weather office said strong, gusting winds will create flurries and a risk of snow squalls on Tuesday.
There could be 10 to 15 centimetres of snow on the ground by Wednesday morning, according to the agency.
Environment Canada said drivers should prepare for poor winter driving conditions, and untreated roads may become snow-covered and slippery.
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The advisory covers London as well as the northern area of southwestern Ontario and also impacts Orangeville and Barrie.