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.

Hurricane Erin is now a Category 5 storm as it rapidly intensified and threatens the Leeward Islands and Puerto Rico, then will move along the U.S. East Coast

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.

Hurricane Erin has been downgraded to a Category 3 hurricane but is gaining in size and raising the risk of life-threatening surf later this week along the U.S.

Hurricane watchers are eying systems in the Atlantic basin. One has a medium chance of developing later this week.