The City of Toronto is under an extreme cold weather alert, with temperatures expected to drop into the double digits during the afternoon and evening.

Though the daytime high on Monday is only -2 C, the mercury is expected to dip quickly during the afternoon, reaching -16 C by Monday evening.

With the wind chill, it will feel more like -25 C by early Tuesday morning, Environment Canada predicts.

The City of Toronto calls extreme cold weather alerts when temperatures dip below -15 C. Alerts are also put in place when factors such as wind chill and precipitation increase the impact of cold weather on health.

During an extreme cold weather alert, residents are asked to check in on those who are especially vulnerable, including the elderly and the homeless. During the alert, two 24-hour drop-in centres are open and additional shelter beds are made available. Shelters are instructed to relax all service restrictions, and transit tokens are available at drop-ins so the homeless can reach shelters.

On Monday morning, provincial police are warned motorists to drive carefully after several weather-related collisions were reported.

The snow began to fall Sunday night, and is expected to continue until Monday afternoon. Environment Canada predicts a total of between two and four centimetres to fall in Toronto. Coupled with wind gusts of up to 50 km/h, visibility could be restricted on open roads.

"Allow extra time for your morning commute. #SeeSnowGoSlow," OPP wrote in a message on Twitter.

Crashes were reported on the Queen Elizabeth Way, Highway 401, Highway 404, Don Mills Road and many other major routes in the GTA.

As a result of the weather, Toronto Pearson International Airport officials are warning travellers to check the status of their fights before leaving home.

At 1 p.m., 29 arriving flights, or 3.7 per cent, had been cancelled. Twenty-two departing flights, or 2.9 per cent, were also cancelled.

Several flights in and out of Billy Bishop Toronto City Airport were delayed on Monday morning, but none had been cancelled.