As Toronto braces for another deep freeze, Mayor John Tory has asked the city to open its warming centres – a response to the recent deaths of two homeless men in as many days.

Environment Canada has issued an extreme cold warning for Toronto, and much of southern Ontario, as a cold front is expected to move in Tuesday night and Wednesday morning. Temperatures could drop to as low as -30 C.

Speaking to reporters Tuesday, Tory requested that the city manager open Toronto’s two 24-hour warming centres, even though an extreme cold weather alert has not been issued by Toronto Public Health (TPH).

“The death of anyone on the streets of Toronto, any single person … is one too many,” he told reporters.

Earlier in the day, a man was pronounced dead after being found unconscious in a downtown streetcar shelter, wearing only a T-shirt, blue jeans and a hospital bracelet.

Paramedics were called to a TTC shelter on the southwest corner of Yonge and Dundas Streets at approximately 5:30 a.m. When they arrived, they found a thin man in his 50s who was unconscious and wasn't breathing.

He appeared to have suffered from a cardiac arrest and hypothermia, paramedics said. He did not have any obvious signs of trauma.

Paramedics tried to resuscitate the man in the back of an ambulance as they rushed to hospital. A police officer who had responded to the call drove the ambulance so the paramedics could work on him while en route to the hospital, but the man could not be revived.

Police said the man was known to them and believed to be homeless.

A vigil was held for the unidentified man Tuesday evening, with a number of residents coming out to lay flowers and light candles.

Policy on cold-weather alerts

Warming shelters typically only open when the City of Toronto is under an extreme cold weather alert, issued when temperatures dip below -15 C overnight.

Alerts can also be called when Environment Canada's forecast includes factors like wind chill and precipitation that increase the impact of the weather on health.

Despite the cold snap that descended on Toronto Monday morning, the city did not call an alert. On Tuesday morning, temperatures reached -20 C with wind chill, but the actual temperature was -14 C, just above the range.

But in a statement released after the opening of the warming shelter, TPH said it expects an extreme cold weather alert will be issued Wednesday morning.

"Low temperatures are expected very early tomorrow morning, reaching -15 C by 9 a.m." it read.

Additional services for the homeless were also announced by the city on Tuesday.

Second death in two days

Meanwhile, another man who police believed to be homeless was found dead in a delivery truck parked in the city's west end Monday.

The man, believed to be in his 50s or 60s, was found at a shipping yard near the intersection of Davenport Road and Wiltshire Avenue at approximately 9 a.m. He was pronounced dead by paramedics on scene.

Toronto Police Const. Jennifer Sidhu told CTV Toronto that the man had been seen in the truck before, and was known in the area.

Police couldn't confirm whether the truck was abandoned, but it was covered in black graffiti when it was found. Temperatures reached -10 C on Monday morning.

Shelters across country preparing for busy nights

As temperatures dip across Canada, shelters are getting ready for an influx of visitors.

In parts of New Brunswick, the mercury is expected to fall below -20C. On the Prairies, it’s closer to -30C, leading to burst pipes and loss of power for the residents of at least one apartment building.

And British Columbia is dealing with its own weather woes – major snowfall that shut down schools in the Okanagan region for a second day.

With a report from CTV’s John Vennavally-Rao