They are among 10 people who have died in Canada, while in the US the death toll has reached at least 17, from traffic accidents and carbon monoxide fatalities.
Utility crews in Canada, and from Maine to Michigan in the US, worked over Christmas to restore power to more than half a million homes that were left in the dark by the ice storm.
Police said two people in Ontario died after using a gas generator to heat their blacked-out home near Toronto.
Quebec police said carbon monoxide poisoning was believed to be the cause of three deaths in a chalet on the province's North Shore.
Earlier, five people were killed in eastern Canada in road accidents blamed on severe weather conditions.
As temperatures plunged below minus 7°C (19°F) in Toronto, the authorities reported a dramatic jump in calls for suspected carbon monoxide poisoning, responding to 110 calls in a 24-hour period.
As the city issued an extreme cold weather alert, Toronto Mayor Rob Ford said: "I understand they want to keep warm, but you cannot do this. This is deadly."
Fire officials warned residents not to use any appliance that burns inside a home and utility firms said some customers could be without power until Saturday.