Temperatures are forecasted to rebound beginning Monday, with a high of -9 C along with possible periods of snow.
"Much of Southern Ontario is on the northern fringe of a major winter storm tracking south of the Great Lakes", said Environment Canada in the special statement.
"If it's too cold for you to stay outside, it's too cold for your pet to stay outside", the warning adds. "Slow down, drive safe", tweeted OPP Sgt. Kerry Schmidt.
The agency says a milder air mass will begin to move in Tuesday.
Plows are also continuing to make their way along city streets.
Skies look to remain clear into the evening, as winds die down to 20-40 km/h. We can expect an overnight low of 15 below zero in the Twin Ports with more wind chill advisories likely to be issued.
FOX 29 meteorologists say frigid temperatures with strong winds up into 35 miles per hour or higher in some areas could cause frostbite on exposed skin in as little as 30 minutes.