A winter storm heading towards the Maritimes is already causing travel delays in the region.

The first major blast of winter is headed toward the region and could dump 20 to 30 centimetres of snow in some areas on Sunday. Winter storm warnings have been issued for all of Nova Scotia and Prince Edward Island and most of New Brunswick​

CBC meteorologist Peter Coade said the storm is expected to arrive first around Grand Mannan, Saint John and Yarmouth and then head North West.

The storm is now in southwestern parts of Massachusetts heading toward Lake Ontario. Most delays and cancellations are affecting flights to central Canada and the north eastern United States.

Smoke on the water cold on Saturday

The cold weather was the talk of the day in Halifax on Saturday. Peter Coade said he expects the leading edge of Sunday’s storm to hit Nova Scotia’s southwest shore and St. Stephen, N.B., around 7 a.m. (Colleen Jones/CBC)

About 15 to 25 centimetres of snow is expected for P.E.I.

Air Canada is advising passengers to call 1-888-351-0807 to reschedule their flights.

Halifax airport spokesman Peter Spurway said people travelling over the next couple of days should check their email because their airline may contact them.

"Airlines are getting much, much better at this. What they do is they tend to look at the schedule and look at the weather and make decisions well in advance. And advise their passengers that the flight’s not going to go so therefore you’ve been booked on this particular flight. This allows travellers to make their travel plans in advance and it also keeps people off the road to the airport,” he said.

Both Air Canada and WestJet are now offering certain travellers the chance to reschedule their flights ahead of the storm without penalty.

For people travelling by boat, Bay Ferries has cancelled its crossing between Nova Scotia and P.E.I.

Have an event cancellation? Check out the CBC Storm Centre

With files from the Canadian Press