Pounding rain, high winds and the threat of heavy snow caused power outages in four provinces, school closures, ferry shutdowns and a rare total closure of Confederation Bridge.
In Nova Scotia, there were more than 30,000 homes and businesses without power at the height of the outages on Thursday afternoon. Hurricane-force gusts toppled trees and even a tractor-trailer.
Police closed Sydney's downtown shopping district because of flying debris.
In Dartmouth, police issued a warning to people to stay away from the downtown because of the danger of items falling off buildings.
All ferries from Nova Scotia to Prince Edward Island, New Brunswick and Newfoundland are tied up.
Confederation Bridge closed at about noon and remained totally shut down for about an hour and a half. It remains closed to high-sided vehicles. This is only the ninth time since Confederation Bridge opened in 1997 that it has closed to all traffic. Wind gusts on the bridge were measured at 136 km/h.
Environment Canada said to expect gusts of 100 kilometres per hour or more in almost every county of Nova Scotia, P.E.I., northern New Brunswick, and the west and north coasts of Newfoundland.
There were still 2,800 NB Power customers in the dark Thursday evening. A spokeswoman for NB Power said most areas without power were expected to be restored later Thursday night. Some outages in Woodstock and surrounding areas may continue until Friday morning.
In P.E.I., 4,300 customers were without power at the peak of the storm, but there were fewer than 10 outages by 5 p.m. The wind warning was still in effect for Thursday evening.
Utilities in Newfoundland and Labrador said poor weather had caused outages, including a tripped wire that knocked out power for 2,000 customers between Deer Lake and Rocky Harbour in western Newfoundland.
Newfoundland Power also said high winds had caused a series of isolated incidents, largely in western Newfoundland but also affecting a neighbourhood in Conception Bay South, near St. John's.
RCMP urged motorists on Newfoundland's Northern Peninsula to stay off regional roads "unless absolutely necessary," noting that winds hitting as high as 150 km/h and driving rain were combining for what the force called treacherous conditions.
Parts of Labrador, meanwhile, were bracing for as much as 40 centimetres of snow.
Snow in N.B.
As well as the high westerly winds, northern New Brunswick is expected to see an estimated 20 centimetres of snow.
School Districts 5 and 15, which cover the English and French schools in northern New Brunswick, cancelled classes. The provincial government has cancelled its French Immersion public consultation session in Campbellton.
The heavy snowfall started around midnight, and by morning, roads were treacherous and thousands were without power.
The northern city of Bathurst had about 16 centimetres of snow fall Thursday.
"Just crazy winds out there because those winds are coming out of the west and northwest direction, the temperature is going to be dropping as we head in towards this afternoon," CBC meteorologist Kalin Mitchell said.
The snow did slow down by mid-day Thursday, but winds remained strong for most of Thursday and that was expected to continue until Friday morning.
The southern regions of the province saw 30 to 40 millimetres of rain and wind gusts up to 76 kilometres an hour.
By Thursday evening, as temperatures dropped, roads in some parts of southern New Brunswick became slippery.
Mitchell said the storm is a "weather bomb."
Marine Atlantic has cancelled all ferry crossings from western Newfoundland to Cape Breton due to high winds in the gulf. Customers are being advised that they should contact the company for updates.
The ferry is tentatively scheduled to resume crossings on Friday at 11:30 a.m., according to the company.