Hurricane Erin has strengthened into a Category 2 storm as it approaches Puerto Rico and the Virgin Islands, bringing heavy rains that could cause flooding and landslides.

A disturbance in the Atlantic following Hurricane Erin is now expected to track northward, according to NHC data.

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.

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.

Beaches are being closed at some locations along the US East Coast as Hurricane Erin threatens rip currents from Florida to New England.

After reaching Category 5 over the weekend, Hurricane Erin is now down to Category 2 but the large hurricane is still causing problems off the East Coast of the U.S.

Hurricane Erin forced tourists to cut their vacations short on North Carolina’s Outer Banks even though the monster storm is expected to stay offshore after lashing part of the Caribbean with rain and wind on Monday.

While the category 4 storm is not expected to make landfall on the U.S. east coast, it will have an impact nonetheless. Dangerous high surf and rip currents are expected from Florida to New England throughout the week.