Toronto has issued an extreme cold weather alert with dangerously low temperatures expected Sunday night.

680News Meterologist Harold Hosein said the mercury will plunge to -18 C overnight.

During an alert — usually called the morning before a frigid night — the city opens up more shelter spaces and encourages the homeless to come indoors.

Shelters also relax restrictions and drop-in centres stock TTC tokens so people can get to the lodgings.

A warming centre at Metro Hall will be open from 3 p.m. until the alert is cancelled. Hot drinks and light snacks will be handed out, and anyone needing a shelter bed can get help.

Alerts are called when Environment Canada predicts an overnight temperature of -15 C or lower without the wind, issues a wind chill warning or predicts extreme weather conditions.

Including Sunday night, Toronto will have been under an extreme cold weather alert for 26 days this winter.