As winds ease on Monday, the warning will be lifted, but temperatures near -20C or colder are still expected Monday night.
Wind chills will drop between 5 and 15 degrees below zero along and west of the Parkway, but the Highlands could be as cold as 25 below zero.
"Cover up", Environment Canada warned. Significant rain is possible Thursday, followed by another blast of Arctic air in time for next weekend.
Skies look to remain clear into the evening, as winds die down to 20-40 km/h.
The advisory means cold air and the wind will combine to create low wind chills, and frostbite and hypothermia can occur if precautions are not taken.
North winds gusting up to 30 km/h are predicted to rise as high as 50 km/h in the morning. Wind chill readings will be between 4 below and 9 above Saturday into Sunday morning, even as wind speeds decrease.
They are reminding people that frostbite can develop within minutes on exposed skin.
It explained that the risks are greater for young children, older adults, people with chronic illnesses, people working or exercising outdoors and those without proper shelter.
It's recommended that pets come in from the cold as well.