An Extreme Cold Warning is in effect for most of northwestern Ontario as meteorologists warn of windchill values near -40.

Environment Canada says cold nighttime low temperatures are expected to continue for the rest of the week, and the risks of frostbite are greater for young children, older adults, people with chronic illnesses, people working or exercising outdoors and those without proper shelter.

Residents are reminded to cover up as frostbite can develop within minutes on exposed skin. And if it’s too cold for you to stay outside, it’s too cold for your pet to stay outside.

Temperatures are expected to improve by Christmas Eve and Christmas Day in northwestern Ontario, as the forecast is calling for sun with a high of minus 17 on Saturday and sun with a high of minus 19 on Sunday.