Irene weakens but remains big threat to US

"We need to remind people, hurricanes are not just a Southern thing. This could be the Mid-Atlantic and the northeast coast," Craig Fugate, head of the Federal Emergency Management Agency, said during a conference call with reporters. "We've got a lot of time for people to get ready, but we don't have forever."

Even if the storm stays offshore, it could cause flooding and power outages all along the Eastern Seaboard. National Hurricane Center director Bill Read drew comparisons to a 1938 hurricane that also approached from the South and killed 682 people in New England.

"We're very concerned about what's going to happen in New England," Read said.

The hurricane's projected path has gradually shifted farther east. Forecasters initially expected the storm to hit Florida.

Irene has already wrought destruction across the Caribbean. In Puerto Rico, more than a million people were without power, and a woman died trying to cross a swollen river in her car. President Barack Obama has declared an emergency there. Hundreds were displaced by flooding in the Dominican Republic, forced to take shelter in schools and churches.

Associated Press writers Curt Anderson in Miami and Martha Waggoner and Michael Biesecker in Raleigh, N.C., contributed to this report.