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.

Storms that ramp up so quickly complicate forecasting and make it harder for government agencies to plan for emergencies. Hurricane Erick, a Pacific storm that made landfall June 19 in Oaxaca, Mexico, also strengthened rapidly, doubling in intensity in less than a day.

At the start of the storm, Hurricane Erin was gauged as high as a catastrophic Category 5 storm with a wind speed of 240 km/h but later was downgraded to Category 4 and then to Category 3.

An eyewall replacement cycle is underway within Hurricane Erin as the monster storm continues to barrel across the Atlantic while bringing gusty winds and rain to Puerto Rico and the Virgin Islands after rapidly intensifying into a catastrophic Category 5 hurricane 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,