Thousands of Canadians are awakening to a dark Christmas, days after a brutal storm that hit southern Ontario and Quebec and is pounding the Maritimes.

In southern Ontario, close to 150,000 customers remained without power as late as Tuesday morning. Early Christmas morning, Toronto Hydro reported about 70,000 people were still without power, compared to 300,000 at the height of the outage.

"We've restored all critical customers (TTC, water services etc), and crews continue to repair priority feeders, which will restore the largest groups of customers at one time," Toronto Hydro said in a Christmas morning release. "Crews will then respond to more localized outages, which affect streets or individual homes."

On Tuesday, Ontario Premier Kathleen Wynne reacted to criticism that power wasn't being restored quickly enough by saying: "So far the progress we're seeing in affected communities is very encouraging,"

"We're three days into this and tens of thousands of people who didn't have power — hundreds of thousands of people who didn't have power — have power now and the progress has been remarkable."

Many customers, however, could be without electricity until the weekend, and Toronto Hydro CEO Anthony Haines said the situation could get worse.

"I can honestly say I've never paid so much attention to the weather forecast before in my life until I did this week," he said Tuesday morning.

"We're expecting 30 km/h winds today, and so it continues to be one of my big concerns that if we see another weather event with trees that continue to be laden with ice and snow, that we'll get additional damage."

Hydro One said late Tuesday afternoon about 39,000 of its customers outside of Toronto remain in the dark. Earlier Tuesday morning the number was around 60,000.

"Right now we're really watching the weather," CEO Carmine Marcello said. "The wind is picking up and we've noticed that that number creeps up and comes back down, so as it stands now we're making great progress … but it is a long, icy road ahead of us."

The utility put out a call on Twitter asking anyone who runs a restaurant that will be open on Christmas Eve or Christmas Day to contact them as the crews working to restore power need food.

'Tonight it will be cold'

The power outages combined with the sharp drop in temperatures have left some residents resorting to dangerous measures to stave off the cold.

Two people were killed in Newcastle, Ont., after it's believed carbon monoxide seeped into their home from a gas generator running in the garage. Police say the generator was being used to help heat the house.

"Do not heat your home with devices that are designed for outdoor use, particularly barbecues or outdoor generators," Wynne said.

"I know that people are trying to stay warm but please be careful and do not put yourselves at risk."

Wynne urged residents with wired smoke alarms and CO detectors to ensure they have battery backups in case of a power outage.

Emergency crews in the Toronto area have responded to more than 100 calls because of carbon monoxide exposure.

"Temperatures should warm up starting tomorrow, which will make it a little easier," Toronto Mayor Rob Ford said at a media briefing Tuesday morning.

"But unfortunately tonight it will be cold. Please help seniors and people with disabilities."

The City of Toronto is running a number of warming centres where residents can seek shelter, food or rest.

In Quebec, about 20,000 customers remained without power on Tuesday, largely in the province's Eastern Townships, as technicians worked to fix power lines and other equipment damaged by the storm.

Light snow in the forecast

Special weather statements are in place in much of southern Ontario as temperatures drop.

Many residents remain without power, and downed trees and power lines pose hazards on many streets. (Galit Rodan/Canadian Press) Temperatures are expected to remain well below freezing until Christmas Day and won't move closer to the freezing mark until the weekend.

"To those who are still without power due to continued challenges in getting the hydro lines up and running, it is advised to seek warm shelter and prepare for the colder than average temperatures that are expected," Environment Canada advised.

"Furthermore, given the well below freezing temperatures, much of the ice will not melt and will likely remain on many surfaces through Christmas and Boxing Day until the end of the week."

The Greater Toronto Area bore the brunt of the storm on Sunday with between 10 and 30 millimetres of ice accumulation bringing down tree limbs and power lines.

Storm hits Atlantic Canada

Meanwhile, an icy mix of rain and freezing rain that hit Atlantic Canada on Monday played havoc with the electricity grid and hampered travel plans.

N.B. Power said more than 45,000 customers were without power in southern New Brunswick today.

The CBC's Catherine Harrop said from Fredericton Tuesday morning that N.B. Power was facing a tough job.

"N.B. Power is saying they're really struggling because, of course, the crews have to work on ice and they're working with those who can take down tree limbs at the same time as the linemen are working on the power lines. So it's a pretty tricky situation."

In Nova Scotia, NS Power said the number of people without power dropped to about 3,300 by this afternoon.

"[The Maritimes are] still dealing with the remnants of the storm which has given a few days' worth of snow, freezing rain and drizzle in some locals," Kennedy said.

Peel Region employee Dwayne Berrigan cuts fallen limbs from iced trees in Brampton, Ont., on Monday. (J.P. Moczulski/Canadian Press) "Tomorrow another system skirts by and Nova Scotia may pick up another two to four centimetres of snow with a light dusting possible in southern New Brunswick."

The storm was expected to hit Newfoundland Tuesday, where residents in some areas were warned to expect as much as 25 centimetres of snow.

Meanwhile, travel in the region was disrupted due to slick roads, while dozens of flights were delayed or cancelled at airports — mainly due to backlogs created by severe weather that also hit Quebec and Ontario.

Passengers were stranded in airports from Toronto to St. John's. Several airlines, including Air Canada, advised passengers to check their flight status before heading to the airport. They also urged passengers to give themselves extra time in case of delays on the road.