Dave Phillips of Environment Canada tells CTV News that Southern Ontario will have every winter condition imaginable throughout the weekend and into Monday.
From mild temperatures to fog and freezing rain and now a deep freeze is on the way for the coming week.
"All the kind of weather you could get in winter in Southern Ontario, we're going to see this weekend and into Monday.
Added Mitch Meredith, a severe weather specialist with Environment Canada: "Right now it's fairly dry and there's a few flurries that are going to cross this evening when the cold front drops down. But then you're looking at temperatures getting below normal and probably some factors due to wind chill over the next week, although the snow squals will be staying away from Windsor."
A special weather statement has been issued by Environment Canada for the London region, calling for fresh frigid Arctic to arrive Sunday night with the coldest weather so far this season expected throughout the work week.
A frigid Arctic air mass is arriving, plunging Southern Ontario into a deep freeze for the upcoming work week.
Extreme cold warnings will likely be required at times during the week due to the combination of cold temperatures and brisk winds.
Temperatures will plunge to well below average values for early January. Minimum temperatures of minus 20 Celcius or below on the coldest days are likely, except for locales right along the shorelines of the Great Lakes and across Southwestern Ontario, where temperatures may bottom out in the minus 15 to minus 20 range.
Significant snow squalls will affect areas to the southeast of the Great Lakes at times.
Meanwhile, the OPP have been dealing with a lot of calls and crashes due to the weather. "It's been pretty busy," says Sgt. Dave Rektor. And he's expecting those calls to keep coming "with temperatures dropping."
There were 322 calls to the West Region OPP over the weekend.
In the Greater Toronto area, OPP had more than 300 calls to contend with.
