Ottawa is urging Canadians to avoid travelling anywhere from South Carolina's Edisto Beach to the North Carolina- Virginia border because of Hurricane Florence.
The government is also warning about travel to Martinique, Guadeloupe and Dominica because of tropical storm Isaac.
Air Canada and WestJet are letting travellers change flights to some areas of the U.S. southeast, Barbados and Hawaii free of charge.
Porter Airlines, out of Billy Bishop Airport, says some of its flights to Newark, New Jersey may also be impacted.