The high winds and heavy rains are also expected to disrupt air traffic along the east coast through the Labor Day weekend, with many flights delayed and others canceled.
"To avoid inconvenience, travelers may wish to delay commencement of their trip," Continental Airlines said in a release today.
Officials in the Northeast have activated emergency centers to monitor the storm closely to determine whether evacuations are needed, and FEMA has also dispatched disaster supplies to Westover, Mass. which will arrive Thursday.
"We are watching like a hawk, day by day, hour by hour," said Steve Levy, chief executive for Long Island's Suffolk County, in New York.
A powerful hurricane such as Earl could affect Long Island, which has about 900 miles of coastline and about 2.7 million people.
New Jersey officials plan to be extra vigilant as the New Jersey shore has more than 1.5 million people.
In Cape Cod, there are more than 200,000 full-time residents and more people are expected to be in the area this holiday weekend.
The biggest fear for officials now is not enough fear.
Joe Williams, commissioner of emergency management for Suffolk County, worried that people are not taking the situation seriously.
"They are still saying, 'What storm?'" he said.
In 1991, Hurricane Bob hit the Northeast and killed 18 people. The infamous hurricane of 1938 left an estimated 700 dead.
On "Good Morning America" today, FEMA Administrator Craig Fugate advised residents along the east coast, and particularly those people visiting from out of town, to have a disaster plan in place and heed evacuation orders.
"You need to make sure you know where to go when you need to go," he said.
The hurricane already has torn through the Caribbean with winds up to 135 miles per hour.
Strong winds flipped over an airplane and tore the roofs off homes in Puerto Rico.
In St. Kitts, waves continued to pound the shoreline as residents used barriers of sandbags to protect their homes.
High winds in St. Martin toppled trees and split some in half, and a once popular fishing port in Virgin Gorda was destroyed.
In Antigua, fallen trees blocked roads and homes were flooded as nearby rivers overflowed.
"A couple boats sank. There was a lot of wind and a lot of rain ... a lot of the streets are flooded, a lot of the villages are flooded out," said Atiba Warner, who witnessed the unfolding scene in Antigua.
ABC News' Michael S. James, Gerard McNiff, Steve Osunsami, Bradley Blackburn and Lee Ferran contributed to this report.
Residents can monitor the hurricane's location on the National Hurricane Center's website.