Poor driving conditions are expected in parts of southern Ontario on Thursday as winter-like weather threatens to cause a major ice storm, Environment Canada says.
With freezing rain and ice pellets on the way, a freezing rain warning is in effect for the City of Toronto, as well as much of the Greater Toronto Area.
The warning also covers the City of Hamilton, Burlington, Oakville, Halton Hills, Milton, Mississauga, Brampton, Waterloo and Oxford, Brant, Niagara, Huron and Perth regions.
The freezing rain warning is an upgrade to a winter storm watch that had previously been issued for the region.
According to Environment Canada, icy conditions are expected when a stronger low-pressure system from the southwest clashes with a colder air mass from the north.
In southern Ontario, rain is expected to change to freezing rain and ice pellets late Wednesday night or Thursday morning.
Periods of freezing rain and ice pellets are expected to last into Friday and may be heavy at times.
From Georgian Bay to eastern Ontario, the wintry mix will arrive Thursday night.
Motorists should be prepared for hazardous driving conditions.
The Thursday morning commute may be challenging with icy conditions from the GTA to Lake Huron, and the conditions may be even more problematic for the evening rush hour, Environment Canada said.
There is a risk that the disturbance could be a major ice storm for a large part of southern Ontario, the national weather agency said.
There could be power outages if ice and strong winds bring down tree limbs or power lines.
There is still some uncertainty about the path of the storm and the extent of the cold air, meaning some communities may fare worse than others.
Southwest of Toronto, Environment Canada is predicting 50 to 80 millimetres of rain for some communities before Friday.
A rainfall warning is in effect from Windsor and Sarnia through London and Brantford.
