About 15,000 people are without power in southern Ontario Sunday morning as the region was hit by another round of freezing rain and ice pellets.

There are numerous cancellations of events planned for the day in London, including church services and a political event, and flight cancellations continue for a second day at the London International Airport.

Environment Canada has issued weather warnings for the entire region for the second day in a row, advising that strong winds could exacerbate already dangerous conditions.

London and region is under both a freezing rain warning and a rainfall alert.

OPP Sgt. Dave Rektor said he was seeing vehicles travelling too fast for the conditions along Highway 402.

"Despite the best efforts of the road crews there is not a lot they can do when the freezing rain is coming down as fast as it is. We're hoping that people will avoid travel this morning unless it is absolutely necessary.

The eastbound lanes of Highway 401 were closed at Colonel Talbot Road due to a jacknifed tractor trailer Sunday morning but have since reopened.

A jacknifed transport near Drumbo also closed a couple of lanes of the 401 Sunday morning.

Environment Canada says freezing rain will change to rain Sunday afternoon.

The rain may fall heavily at times with amounts likely in the 20 to 30 mm range, the agency say.

Some additional rainfall is likely overnight into Monday, albeit lighter. Total rainfall amounts for the weekend may be in the 30 to 40 mm range with localized amounts of 50 to 60 mm possible.

Provincial power utility Hydro One says it has extra crews on standby to address outages as the massive, slow-moving storm system hammered an area that stretches from Windsor into Quebec and from Lake Ontario to North Bay.

Ontario Provincial Police have said there were more than 550 crashes on highways surrounding Toronto on Saturday -- none of them fatal -- and that there had been dozens more early Sunday.