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.

Additional strengthening is expected as the storm is forecast to “remain a large and dangerous major hurricane through the middle of this week,” the National Hurricane Center said.

Powerful Hurricane Erin has undergone a period of astonishingly rapid intensification — a phenomenon that has become far more common in recent years as the planet warms. It was a rare Category 5 for a time Saturday before becoming a Category 4, churning through the Atlantic Ocean north of the Caribbean.

Hurricane Erin is pelting parts of the Caribbean and is forecast to create dangerous surf and rip currents along the U.S. East Coast this week.

Erin was a Category 3 hurricane Sunday morning, the National Hurricane Center said in its 8 a.m. update, with sustained winds of 125 mph, with tropical storm-force winds reaching out 205 miles.

Tropical storm watches expand from the Virginia beaches to Fenwick Island, Delaware, including Ocean City, Maryland.

Hurricane Erin soaked Puerto Rico with heavy rains, causing power outages, flight cancellations, and flooding.