Toronto and most of Ontario are bracing for a bout of bitterly cold temperatures.

Environment Canada has issued an extreme cold warning for Toronto and much of the province.

“Bitterly cold wind chills near -30 are expected overnight and into Friday morning,” the weather agency said in its warning Thursday.

The city sat at -7 C Thursday afternoon, but that temperature is expected to plummet to a low of -21 C overnight, feeling closer to -30 with the wind chill.

In its warning, Environment Canada reminded people to keep emergency supplies such as blankets and jumper cables in their cars and advised people not to allow pets to stay outdoors for prolonged periods.

Extreme cold temperatures raise the risk for frost bite and hypothermia and those who work outdoors are being advised to take regular breaks during the extreme cold spell.

The City of Toronto has also issued its own extreme cold weather alert for the city ahead of the bone-chilling temperatures. Alerts are issued whenever the temperature could reach approximately -15 C or colder, or when the wind chill is forecast to reach -20 or colder.

During the alert, Metro Hall on John Street will host a warming centre, continuing until noon on the day the alert is ended.

Other services activated during the alert include expanded services at community agencies, transit tokens and tickets for vulnerable people and more street outreach.

Environment Canada says Toronto will see a high of just – 8 C on Friday, and a low of – 12 C, with the wind chill making it feel as cold as – 28 C in the morning.

Overnight from Friday into Saturday, a low of -17 is expected, feeling closer to -25 with the wind chill.

The cold is expected to wane by Saturday, with the temperature expected to hover somewhere between -4 C and -1 C.