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

Forecasters say Hurricane Erin has exploded into a Category 5 storm in the Atlantic Ocean just north of the Caribbean.

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.

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.

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

SAN JUAN, Puerto Rico (AP) — Erin strengthened into a powerful Category 4 hurricane in the Caribbean on Saturday and continues to intensify, the National Hurricane Center said. The storm is 150 miles northeast of Anguilla with maximum sustained winds of 145 mph. It is moving west-northwest at 20 mph (31 kph).

Hurricane Erin rapidly intensified into an extremely dangerous Category 5 cyclone as it stayed safely north of the Caribbean islands over the weekend.

Tropical Storm Erin on Wednesday continued to push west through the Atlantic with it forecast to become the season’s first hurricane, growing to major hurricane strength by the weekend,