(CNN) — That last bit of summer vacation is likely to be less relaxing than anticipated for travelers spending Labor Day weekend along the Southeast coast of the US and in the northern Bahamas.

Hurricane Dorian , currently a Category 5 storm, is tearing through the Abaco Islands in the Bahamas. It's expected to strike Grand Bahama, the northernmost island in the archipelago, late Sunday or early Monday before it nears the US coast, forecasters say.

The National Hurricane Center called the weather event in the Abaco Islands "life-threatening," with reports of 220 mph wind gusts and a storm surge of 18 to 23 feet above normal tide levels.

Pelican Beach Villas, also in the Abaco Islands, told CNN via email that they currently have no guests on site and are closed for the storm. "Pelican Beach Villas is right in the water's edge, so we could not accommodate any guests," wrote General Manager Alan Hamilton.

Dorian may hit the Southeast coast

Florida may be spared the worst of the storm after all, although the Sunshine State still faces dangerous conditions in the coming days. Even if the storm doesn't make landfall in Florida, its proximity to the coast could cause substantial damage.

Meanwhile, Georgia, South Carolina and North Carolina are now on high alert for possible landfall later in the week.

Hurricane Dorian's shifting path means abrupt changes for people traveling this holiday weekend. While the forecast looks better than anticipated in some places, in others, it has led to both immediate emergency evacuations and increased caution.

"High surf and very dangerous rip currents are expected all along the East Coast from Florida up through the Carolinas through the weekend," said CNN Senior Meteorologist Dave Hennen.

Cumberland Island National Seashore, on the largest barrier island off the Georgia coast, closed to the public on Saturday. Fort Frederica National Monument, located on nearby St. Simons Island, also closed on Saturday, according to a National Park Service press release.

The National Park Service noted a high risk for dangerous rip currents along Cumberland Island National Seashore beaches.

Both parks will remain closed until after the storm passes and the areas are deemed safe.

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Flights and trains are being canceled

As of Sunday morning, airlines had canceled over 335 Sunday flights to/from/within the United States and about 609 flights on Monday, according to flight tracking site FlightAware.com

Airlines have been issuing waivers for several days to travelers headed for destinations in the storm's projected path.

Destinations in Georgia and the Carolinas have joined airline advisories as the storm progresses northward.

Orlando International Airport said it would remain open on Monday in light of the storm's shifting path. It initially announced it would cease operation at 2 a.m. Monday local time.

Cruise ships are changing itineraries

The storm's proximity to the Bahamas has prompted cruise lines to modify some of their itineraries by shortening or lengthening cruises and rerouting to different ports of call.

Aubrey Manzo Dunn, a spokeswoman at Cruise Critic, says 45 cruise sailings have been affected across seven lines: Carnival, Disney, Norwegian, Royal Caribbean, Celebrity, Bahamas Paradise Cruise Line and MSC.

Based on double occupancy, these cruise changes could impact nearly 135K travelers, Dunn estimates.

On its website, Carnival Cruise Line listed a series of sailings that it is monitoring or modifying out of Port Canaveral, Port of Miami, Jacksonville, Fort Lauderdale and Tampa in Florida and in Charleston, South Carolina. The advisory outlines how passengers can sign up for text alerts for more information.

Disney Cruise Line posted an operations advisory on its website . While the August 31 Disney Fantasy sailing was expected to proceed as planned, Disney Dream's scheduled September 2 sailing will depart on September 4 with a shortened, two-night itinerary. Full details for re-booking and refunds are available online

Amusement parks and other attractions are on alert

In Orlando, about 50 miles inland from Florida's Atlantic coast, Walt Disney World was operating under normal conditions Sunday.

Universal Orlando Resort was also monitoring the situation, the company said.

Kennedy Space Center Visitor Complex, one of Central Florida's most popular tourist destinations, was expected to be closed Sunday and Monday because of the storm. The center moved its $650 million Mobile Launch Platform inside on Friday.

Hilton Head Island to evacuate Monday

Dorian isn't forecast to hit Hilton Head Island in South Carolina until Thursday as a downgraded Category 2 storm, but officials have moved to cut Labor Day vacations short.

South Carolina Gov. Henry McMaster announced mandatory evacuations for several counties in the state , including Beaufort County, home to Hilton Head. They go into effect Monday at noon.