As temperatures dip Sunday, Toronto’s chief medical officer has issued an extreme cold warning for Toronto until further notice.Dr. Eileen de Villa is warning members of the public to dress in warm layers, stay dry and seek shelter when outdoors — and to check on family, friends and neighbours with heart or respiratory conditions, or those who spend long periods of time outside.Environment Canada forecasts a low of -15 C with the windchill Sunday, but the city is expected to get even colder Monday with a wind chill low of -23 C. (Rene Johnston / Toronto Star file photo)“Depending on the wind chill, exposed skin can freeze in minutes,” the warning reads.The city issues extreme cold alerts when the daily forecast reaches -15 C, or -20 C with wind chill. On Sunday, temperatures will hover around -9 C for most of the day, according to Environment Canada, dropping to a low of -15C with the windchill around 11 p.m. The city is expected to get colder on Monday with a wind chill low of -23 C.The alert means a warming centre at Metro Hall will be open by 7 p.m., and will remain open until noon the day the alert ends.“The City asks that residents help vulnerable people by calling 311 if there is a need for street outreach assistance. Call 911 if the situation is an emergency,” the warning reads.Environment Canada has issued no weather alerts for the city.Jack Hauen is a breaking news reporter, working out of the Star’s radio room in Toronto. Follow him on Twitter: @jackhauenTOP STORIES, DELIVERED TO YOUR INBOX.