Nova Scotia Power reported outages throughout the province as winds gusting to 100 kilometres an hour brought down tree limbs and power lines.
Heavy rain soaked much of the Maritimes while snow fell in parts of New Brunswick as far south as Saint John.
The City of Saint John sent out a notice urging drivers to use caution as crews were heading out to sand and salt the city's roads.
NB Power reported electrical outages to about 3,100 customers.
RCMP in eastern Prince Edward Island said a driver was killed near Pooles Corner early Sunday and that road conditions were a factor in the death.
The strong winds led to the closure of the Confederation Bridge to P.E.I to cars towing trailers, motorcycles, recreational vehicles, trucks and buses.
In Nova Scotia, the Englishtown ferry — a short crossing across St. Ann's Bay in northern Cape Breton — shut down due to strong coastal waves.
Up to 60 millimetres of rain was forecast for most of Nova Scotia while parts of western New Brunswick expected up to 15 centimetres of snow.
The storm battered the eastern United States earlier, causing four U.S. states to declare emergencies and causing at least three deaths.
The severe weather has also knocked out power to millions and snarled air and highway travel from Maryland to Maine.
Numerous flights between Canada and many U.S. cities, including Washington, New York and Chicago, were cancelled.