The city’s acting medical officer of health has issued an extreme cold weather alert for Toronto, with frigid temperatures set to hit the city.

The temperature is expected to range between -4 C and – 11 C in the city today according to Environment Canada. However it is expected to feel as cold as -20 C with the wind chill overnight.

The weather on Thursday is expected to be similar with a temperature of -6 C with flurries and blowing snow in the afternoon. Temperatures will dip to -16, without factoring in the wind chill. Winds will be gusting up to 50 kilometres an hour, Environment Canada said, and there could be around 2 centimetres of snow.

Friday will be sunny with a mix of clouds, but temperatures will stay around -6 C during the day, the weather agency said.

Saturday there will be a break from freezing weather, however, a combination of rain and snow is expected to hit Toronto. The deep chill returns Sunday with an expected low of -13 without the wind chill. Temperatures will continue to stay below the freezing mark into the following week.

The city issues extreme cold weather alerts when the temperature is forecast to reach -15 C or colder, or when the wind chill is forecast to reach -20 or colder.

The alert triggers extra shelter spaces for the homeless and other cold-weather related services.

“Those most at risk of cold-related illness are people experiencing homelessness or those underhoused, those who work outdoors, people with a pre-existing heart condition or respiratory illness, elderly people, infants and young children,” the city said in its alert. “People with heart problems can experience worsening of their condition up to several days after cold weather occurs.”

The alert will be in effect until it is terminated by the city.

During an extreme cold weather alert, the city advises residents to take a number of steps, including:

  • Dress in layers, making sure your outer layer is windproof, and cover exposed skin.
  • Wear a hat, warm mittens or gloves, and warm boots.
  • Stay dry. Your risk of hypothermia is much greater if you are wet.
  • Choose wool or synthetic fabrics for your clothes instead of cotton, because cotton stops keeping you warm once it gets wet.
  • Seek shelter if you normally spend long periods outside. Depending on the wind chill, exposed skin can freeze in minutes.
  • Drink warm fluids, other than alcohol.
  • Warm up by taking regular breaks in heated buildings when enjoying winter activities outside.
  • Consider rescheduling outdoor activities, or limiting time outdoors, during colder temperatures, especially if it's windy.
  • Heat your home to at least 21ºC if infants or elderly people are present.
  • Call or visit vulnerable friends, neighbours and family to ensure they are not experiencing any difficulties related to the weather.