Hurricane Erin explodes in strength to a Category 5 storm in the Atlantic

SAN JUAN, Puerto Rico — Hurricane Erin exploded in strength into a Category 5 storm in Atlantic waters just north of the Caribbean on Saturday, rapidly powering up from a tropical storm in a single day, the National Hurricane Center said.

Though the compact hurricane’s center wasn’t expected to hit land, it threatened to deliver flooding rains to Puerto Rico and other populated areas as it continued to grow.

The first Atlantic hurricane of 2025, Erin ramped up from a tropical storm to a Category 5 hurricane in 24 hours. By late Saturday morning, its maximum sustained winds more than doubled to 160 mph.

Mike Brennen, director of the National Hurricane Center in Miami, said Erin had swiftly grown into a “very powerful hurricane,” racing from maximum sustained winds of 100 mph to 160 mph in nine hours.

The Hurricane Center said Erin should begin to slowly weaken Monday as the storm encounters increased wind shear. However, forecasters predicted it will remain a major hurricane until late in the week.

The U.S. government has deployed more than 200 employees from the Federal Emergency Management Agency and other agencies to Puerto Rico as a precaution as forecasters issued a flood watch for the entire U.S. territory from late Friday into Monday.

Puerto Rico Housing Secretary Ciary Pérez Peña said 367 shelters had been inspected and could be opened if needed.

The U.S. Coast Guard said Friday that it closed six seaports in Puerto Rico and two in the U.S. Virgin Islands to all incoming vessels unless they had received prior authorization.

The hurricane remained a Category 5 storm Saturday evening, when it was located 135 miles northwest of Anguilla and moving west at 15 mph. The storm’s center was forecast to remain at sea, passing 145 miles north of Puerto Rico, according to the National Hurricane Center.

Tropical storm watches were issued for St. Martin, St. Barts and St. Maarten. The National Hurricane Center warned that heavy rain in some areas could trigger flash flooding, landslides and mudslides.

Tropical-storm-force wind gusts are possible in the Turks and Caicos Islands and southeast Bahamas.

Officials in the Bahamas said they prepared some public shelters as a precaution as they urged people to track the hurricane.

“These storms are very volatile and can make sudden shifts in movement,” said Aarone Sargent, managing director for the Bahamian disaster risk management authority.

Though compact in size, with hurricane-force winds extending 30 miles from its center, Erin was expected to double or even triple in size in the coming days, the National Hurricane Center said. That means the storm could create powerful rip currents off parts of the U.S. East Coast next week, even with its eye forecast to remain far offshore.

Protruding U.S. coastal areas — such as North Carolina’s Outer Banks, New York’s Long Island and Cape Cod in Massachusetts — face a higher risk of direct and potentially severe tropical storm or hurricane conditions than much of the southern Atlantic, mid-Atlantic and northern New England coasts, AccuWeather said.

Hurricane specialist and storm surge expert Michael Lowry said Erin gained strength at a pace that was “incredible for any time of year, let alone Aug. 16.”

Lowry said only four other Category 5 hurricanes have been recorded in the Atlantic on or before that date.

The most powerful storms tend to form later in the year, with the hurricane season typically peaking in mid-September.

In October 2005, Hurricane Wilma rocketed from a tropical storm to a Category 5 in less than 24 hours, according to National Hurricane Center advisories from that time. Wilma weakened to a Category 3 hurricane before striking Florida. And in October 2007, Hurricane Felix took just over a day to go from a tropical storm to Category 5.

Including Erin, there have been 43 hurricanes that have reached Category 5 status on record in the Atlantic, said Dan Pydynowski, senior meteorologist at AccuWeather, a private forecasting company.

“They’re certainly rare, although this would mark the fourth year in a row that we’ve had one in the Atlantic basin,” Pydynowski said. Conditions needed for hurricanes to reach such strength include very warm ocean water, little to no wind shear and being far from land, he said.

Scientists have linked rapid intensification of hurricanes in the Atlantic Ocean to climate change. Global warming is causing the atmosphere to hold more water vapor and is raising ocean temperatures. The warmer waters give hurricanes fuel to unleash more rain and strengthen more quickly.

Storms that grow so quickly complicate forecasting for meteorologists 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.

Erin is the fifth named storm of the Atlantic hurricane season, which runs from June 1 to Nov. 30. It’s the first to become a hurricane.

The 2025 hurricane season is expected to be unusually busy. The forecast calls for six to 10 hurricanes, with three to five reaching major status with winds of more than 110 mph.

Coto writes for the Associated Press. AP writer Isabella O’Malley in Philadelphia contributed to this report.