More rain and high winds are expected as Irene continues to lash New Brunswick and plunge people in the dark.
Up to 4,000 homes and businesses were without power by 8 p.m. AT Sunday. There were hundreds of outages earlier in the day, well ahead of Irene's arrival from the eastern United States.
NB Power spokeswoman Jessica Gallagher said the "storm room" was co-ordinating restoration efforts.
The centre of the storm was expected to move into the Maritimes and Quebec late Sunday and into Monday. Irene was downgraded to a post-tropical storm as of 10 p.m. AT.
CBC meteorologist Peter Coade said up to 50 millimetres of rain had fallen on some parts of southern New Brunswick by 3:30 p.m. AT Sunday, when the massive storm was south in Massachusetts.
"We've already had a lot of rain in New Brunswick and that's going to continue because of the path of the actual centre of the storm is up through New England and into northwestern New Brunswick," he said.
And as the tropical storm moves north, it will bring high winds, Coade said.
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A wind warning remains in effect, along with a warning of heavy rain.
The Emergency Measures Organization warns of rising water levels over the enter St. John River basin for the next 72 hours. People in the area are urged to pay close attention to levels and have an emergency plan.
"Prepare now to ensure your family is safe," the department said in a statement.
CBC reporter Dawn MacPhee saw a lot of rain as she travelled from Fredericton to Edmundston, near the Quebec border, Sunday afternoon. It was still raining heavily at 9 p.m.
"Heavy rain continues to fall in Edmundston, but the wind has barely picked up. It's just enough to wave flags," she reported.
About 100 mm or more of rain was expected in the area, where water levels are already high after a wet summer.
To prepare for the storm, officials lowered the floodgates at the Madawaska River dam to try to lower the water level and make room for more rain.
In Fredericton, police urged people to stay off the roads after 3 p.m.
"There could be some potential flooding on the roadways, which could cause some hydroplaning," said Sgt. Matt Myers, adding that high winds could knock down trees.
Drivers in other parts of the province appeared to be heeding the warning. Police in the Kennebecasis Valley, near Saint John, said the roads were quieter than usual.
There was one report of a driver going off the road in the area because of the slick conditions. There was no word on injuries.
A tropical storm warning remains in effect for the Fundy coast, where a storm surge could mean high waves and a pounding surf.
Ferry crossings between Saint John, N.B., and Digby, N.S., are on hold until Monday afternoon.
Two cruise ships altered their schedules because of the storm. The Caribbean Princess cancelled its Saint John port visit altogether, while the Carnival Glory will arrive on Tuesday instead of Monday.
There were a few flight cancellations at the Moncton airport.