Forecasters have predicted Hurricane Earl is on track to possibly make landfall in North Carolina on Thursday.
The slightest shift in its path could make the Category 4 storm either strike the East Coast or remain at sea.
Puerto Rico took the brunt of the storm Monday night, pummeled by Earl's sustained winds of 135 miles-per-hour.
The storm flooded streets, destroyed homes, and forced several cruise ships to remain docked in harbors.
Presently, weather forecasts call for the storm to cross the Caribbean, remaining on a direct collision course with the East Coast.
"People really need to pay attention to what's going on over the next couple of days," said Richard Muth, director of the Maryland Emergency Management Agency.
The National Hurricane Center is warning residents from North Carolina to Maine to brace themselves for the storm. It's expected to bring heavy rain, gusting winds, and dangerous riptides.
Already, lifeguards along the East Coast have rescued hundreds of swimmers caught in deadly rip currents.
"We have a channel of water moving about a foot a second," said Rod Alusie, chief of the Atlantic City Beach Patrol. "That speed increases as wave height increases and wave force increases. You can go backwards about eight feet a second."
Earl's timing couldn't be any worse. The Category 4 storm is crashing the Labor Day holiday, one of the busiest summer beach weekends.
"We do have some beaches closed," Alusie said. "We have the most dangerous, most populated beaches fully protected."
Safety experts are urging travelers to be extremely careful. Over the weekend in Ocean City, Md., a 23-year-old father and boyfriend went missing after a swim. A local TV crew interviewed the man's girlfriend shortly after he disappeared.
"I felt something was wrong with him, so I kept calling his phone," said Jakeline Ruiz-Reyes, the swimmer's girlfriend. "I got no answer."
She spent the next day looking out to sea, but could not find him. The local Beach Patrol believes he was caught by a riptide from Hurricane Danielle.
One bit of good news is that its current path will keep Earl clear of major gas and oil rigs in the Gulf of Mexico.
However, forecasters said if Earl swings farther to the west, it could produce heavy rain along the Interstate 95 corridor from North Carolina to Washington, D.C. to New York.