Cancellations, road closures and power outages piled up Wednesday as a blanket of freezing rain pelted southern Ontario.

Freezing drizzle advisorieswere in effect as of 2:30 p.m. EST for a portion of southern Ontario stretching from Windsor through the Greater Toronto Area and all the way to Montreal.

The worst of the system has moved through Ontario and is now above parts of southern Quebec, which as of Thursday evening is under a freezing rain warning. The storm is expectedto arrive in the maritimes by Thursday night, dropping freezing rain on New Brunswick, Nova Scotia and Prince Edward Island on Friday.

Earlier Thursday, Hydro One, which mainly provides electricity to rural parts of Ontario, was reporting power outages affecting more than 3,000 properties. One large outage along the Lake Erie shore near Port Rowan, Ont., was affecting more than 2,000 properties. There were also reports of power outages in Toronto, Hamilton and St. Catharines, Ont.

School buses were cancelled in many parts of southern Ontario Wednesday in advance of the arrival of the freezing rain. Some school boards decided to close all their schools for the day, either because of poor conditions in the morning or because of concerns the situation could deteriorate by the afternoon. Canada Post said it had suspended mail delivery to some parts of southern Ontario.

The weather also made for difficult driving conditions, with several major roads and highways being closed at times Wednesday. All westbound lanes of Highway 401 were blocked near London, Ont., for a period of time due to an issue involving a tractor-trailer.

While the freezing rain blanketed southern Ontario, other parts of Canada were dealing with some of their coldest weather of the year.

Extreme cold warnings are in place for most of Alberta and Saskatchewan as well as parts of British Columbia, Manitoba and the Northwest Territories. Environment Canada said wind chill values were expected to be between -40 and -50 in Edmonton and Saskatoon, and between -50 and -55 in Yellowknife on Wednesday, with conditions starting to ease during the day on Thursday.

A separate storm was hitting northern Ontario. Environment Canada issued a snowfall warning for Thunder Bay, Ont., and its surrounding area, saying snow would continue to fall through Thursday. Total accumulation levels could reach 25 cm, the agency said.