Hurricane Erin exploded in strength to a Category 5 storm in the Caribbean on Saturday, rapidly powering up from a tropical storm in a single day, the National Hurricane Center said.

As of 5 a.m. on Sunday, Hurricane Erin has weakened back to a Category 3 storm but has grown larger, the National Hurricane Center said.

Hurricane Erin is expected to steer clear of the U.S. East Coast, but its massive impacts could include rip currents on American beaches.

It quickly powered up from a tropical storm to a Category 5 in a single day, the National Hurricane Center said.

Despite this, the US National Hurricane Center (NHC) says Erin is growing in size, with tropical-storm-strength winds extending 205 miles from its centre. Storm-related hazards, including flash flooding and landslides, are expected in the Virgin Islands and Puerto Rico.

BEAUMONT, Texas — Tropical Storm Erin is moving quickly westward across the Atlantic Ocean and could strengthen into a hurricane by late Thursday, prompting the National Hurricane Center to advise residents of the northern Leeward Islands, Virgin Islands and Puerto Rico to monitor the storm's progress.

Officials in the northern Caribbean are warning of heavy rains and dangerous swells as Tropical Storm Erin approaches the region.