A polar vortex, bringing dangerously cold temperatures, is expected to sweep into Ontario this weekend.
Environment Canada Warning Preparedness Meteorologist Steven Flisfeder said daytime high temperatures of about -10 C to -15 C, with overnight lows close to -20 C, are expected.
"We'll start to see temperatures drop through the day Saturday, overnight Saturday into Sunday will be very cold. That cold will remain in place for pretty much the entirety of Sunday, all the way through to about Thursday," said Flisfeder.
He said it's important to remember that frostbite can develop in minutes on exposed skin.
"With these kinds of temperatures the more exposure you have -- that means time outdoors but also exposed skin -- the risk of frostbite is always present," said Flisfeder. "So, it's important to limit your time outdoors, cover up as much as you can with hats, mitts, scarves, coats, layers -- especially if you'll be spending lots of time outside -- and stay dry as well, because that will help protect you from the cold."
Flisfeder expects the temperature will get a bit warmer toward the end of the week, but not by much.
"It will still be a couple of degrees colder than normal. Normal daytime highs for this time of year should be about - 2 C. It probably won't make it quite to that point, but relative to the week ahead, it will definitely feel much, much, warmer," he said.
Flisfeder said a temperature plunge like this hasn't been experienced in this region in about two years.
Meanwhile, Lambton Public Health issued a Cold Weather Alert on Friday afternoon, which will take effect Monday.
This comes as the temperature is expected to meet the threshold of -15 C in the overnight hours.
The alert is expected to remain in effect until Wednesday, January 22.
Lambton Public Health is advising local agencies that provide shelter and assistance to individuals experiencing homelessness to prepare for an increase in demand.
A list of warming centres can be found on Lambton Public Health's website.
