Toronto has issued an "Extreme Cold Weather Alert," warning residents to beware the perils of frigid temperatures now gripping the city.

The alert issued by the City of Toronto Monday morning "is in effect until further notice."

In the event of such alerts, the city ramps up efforts to protect the people most vulnerable to the cold.

Measures include:

easing of rules at homeless shelters, so that people are not turned away without alternate accommodations

the opening of 172 additional overnight shelter spaces

an increase in overnight outreach on downtown streets

distribution of TTC tokens at some drop-in centres

An alert is typically issued when Environment Canada predicts a temperature of -15 C or lower, without wind chill.

According to the agency's latest forecast, the temperature is expected to dip to -13 C overnight Monday.

Forecasters are calling for the cold trend to continue throughout the week, with temperatures hitting a low of -20 C on Wednesday night.

Anyone seeking information on accessing city services during the Extreme Cold Weather Alert can call the city's 311 telephone information line, or contact the Central Intake line directly at 1-877-338 3398.

The Streets to Homes Assessment and Referral Centre located at the intersection of Peter and Richmond Streets is also open 24 hours a day. People who want a respite from the cold, but do not want a shelter bed are invited to visit there anytime.