Toronto to see big temperature swing this weekend as bitter cold arrives next week

Toronto will miss the worst of any lake effect snow bands, with as much as 2 centimetres of snow expected for Thursday.

Toronto is set to see some bitterly cold temperatures next week as a blast of arctic air descends on parts of Canada and the United States.

Environment Canada is calling for a high of 2 C on Friday but by Saturday afternoon, the daytime high will dip to -4 C, feeling closer to -10.

CP24 Meteorologist Bill Coulter says seasonable temperatures will give way to frigid conditions starting Sunday, bringing temperatures that could feel as cold as the -20s with the wind chill.

“A bitter intrusion of arctic air will then be in place through to next Thursday. You’ll be needing to pull out the parkas to stay warm,” Coulter said.

“That extremely cold air will arrive in the wake of a system that is expected to bring wet snow Saturday morning and midday. Bitterly cold air will then flood over central and eastern parts of Canada and the U.S.”

The cold comes amid a disrupted polar vortex, Coulter said.

What is a polar vortex?

Coulter said a polar vortex in is a circulation of strong westerly winds that forms in the stratosphere, usually between 15 to 50 kilometres above the North and South poles every winter.

“When the polar vortex is strong, it keeps the coldest air up in the arctic. When that circulation weakens, it can spread or split in two and begin to interact with a wavy polar jet stream in the troposphere and bring that extremely cold air closer to the surface and farther south,” he said.

“At the same time, it can drive warmer air up into the polar region and can create melting of polar ice.”

How cold is it going to get?

There will be a significant temperature swing in Toronto over the weekend. Saturday will see a daytime high of 1 C before dropping off to a high of -8 C on Sunday and Monday. Tuesday’s forecast will be even colder, with an expected daytime high of -11 C and a low of -17 C. The temperature will likely feel colder is some areas when factoring in the wind chill.

Will this be the coldest weather we’ve seen this winter?

The lowest daytime high recorded at Toronto Pearson Airport this winter was -8.7 C on Dec. 22. If Tuesday’s forecast is correct, it will be the coldest day of the season thus far.

What is the city doing to help vulnerable people during the cold snap?

The city says warming centres are activated when temperatures reach -5 C and/ or when Environment and Climate Change Canada issues a warning about a winter weather event.

“Once activated, warming centres remain open 24 hours a day until it is determined that locations will close due to a rise in temperature,” the city said in an email.

“Once a warming centre closes to new admissions, staff work to refer individuals who remain onsite to alternate spaces in the shelter system.”