Toronto's medical officer of health has issued an extreme cold weather alert for the city on Sunday because the temperature is expected to plunge to –17 C overnight.

Environment Canada says it will feel like –24 with the wind chill.

Dr. Eileen de Villa issued the alert to warn residents of the expected drop in temperature.



Such alerts are issued when Environment Canada predicts the temperature will be –15 C or colder or when it will feel like –20 with the windchill.

The alerts activate city services that are focused on getting and keeping vulnerable residents inside.

Mitch Olner clears snow off of his car with a hockey stick in Toronto. There's a 60 per cent chance of flurries on Sunday afternoon, evening and after midnight. (Christopher Katsarov/Canadian Press)

On the day that an alert is issued, a warming centre at Metro Hall is opened by 7 p.m. and it remains open until 12 noon on the day it is terminated.

Also, the alerts prompt community agencies to relax service restrictions, make TTC tokens available at some drop-in centres and provide additional overnight street outreach.

Deep freeze begins Sunday night

"Exposure to cold weather can be harmful to your health," the city said in a news release on Sunday.

According to Environment Canada, the forecast calls for a 60 per cent chance of flurries on Sunday afternoon, evening and after midnight.

Sunday's high temperature is forecast to be –3 C in the afternoon and –17 C on Sunday night.

The city reminded residents that those most at risk of cold-related illnesses are people who are homeless or under-housed, people who work outside, those with a heart condition or respiratory illness, as well as the elderly, infants and young children.