Hurricane Erin has restrengthened to a Category 4 storm as it turns northwest and is expected to remain east of the U.S., according to the National Hurricane Center.

Erin became a Category 3 hurricane in the Caribbean early Saturday and is expected to strengthen further during the day, the National Hurricane Center reported.

More than 159,000 customers were without power in Puerto Rico as a result of Hurricane Erin on Sunday morning, according to Luma Energy, a private company that oversees the transmission and distribut...