A low-pressure system developing in the northeastern U.S. today has prompted blizzard warnings for much of the Maritimes, where there are already travel cancellations.

Environment Canada warns that a powerful storm expected to hit the eastern U.S. will make its way northeastward towards the Maritimes on Monday night and into Tuesday.

The national weather service has upgraded the winter storm warnings to blizzard warnings for Nova Scotia, New Brunswick and P.E.I.

"Blizzard warnings are issued when widespread reduced visibilities of 400 metres or less are expected for at least four hours," according to Environment Canada.

The storm is forecast to bring heavy snow and strong winds gusting up to 90 km/h, with higher gusts possible along the Fundy and Atlantic coasts. The winds combined with snow are expected to cause visibility problems.

"Travel is expected to be hazardous due to reduced visibility," says Environment Canada. "If you become stranded in a vehicle do not leave. The vehicle offers a form of protection from the cold. A single person walking through the snow is harder to find than a stranded car or truck. Ensure that shelter is provided for pets and outdoor animals."

Nova Scotia, New Brunswick and Prince Edward Island are expected to get between 15 and 30 centimetres on Tuesday. In Nova Scotia, that snow will mix or change to ice pellets by the afternoon.

CBC meteorologist Peter Coade said he expects the stormy weather to persist through Wednesday.

"The snowfall totals forecast in today’s weather for tomorrow are up to early tomorrow evening," Coade said.

"As the storm will continue tomorrow night and into Wednesday, more snow will fall as indicated herein. At this time, it is rather difficult to forecast with a great deal of accuracy the 18-hour snowfall after tomorrow evening."

Some flight cancellations have already begun

Nova Scotia's Department of Transportation is still cleaning up after Saturday's torrential rainfall. Some roads in Lunenburg and Colchester counties remain closed.

Park Street between Bible Hill and Truro remains closed Monday morning due to flooding and ice.

The first snowflake hasn't even fallen here, but already several flights from Halifax to the eastern U.S. have been cancelled ahead of a powerful storm expected to hammer the eastern United States.

That could cause a ripple effect for travellers across the board.

In anticipation, WestJet and Air Canada are already offering free rebooking for people who were planning to travel Monday to New York and Boston.

Marine Atlantic had to postpone some of its weekend sailings between Nova Scotia and Newfoundland and Labrador until Monday, but there could be even more delays. The ferry company says it's watching the weather on the Cabot Strait ahead of the impending storm.