Toronto's Medical Officer of Health Dr. David McKeown issued the alert Sunday morning with the temperature sitting at -9 C, but feeling like -17 C.
Sunday's high is -1 C, but it appears the city has not shed it's winter weather just yet — the overnight low is -14 C with Monday's high forecast for -2 C.
The alert will remain in effect until further notice.
The decision to issue an alert makes extra services available for homeless Torontonians, including additional shelter beds.
The public is reminded to check in on vulnerable people they know to ensure they are safe.
Anyone who sees a person on the street needing outreach assistance should call 311.