Hurricane Erin briefly strengthened into a Category 5 storm. It is not expected to make a direct hit on the U.S. but will create dangerous surf.

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.