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.

Multiple warnings were in effect along the East Coast on Wednesday, as officials warned of a "life-threatening" situation.

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.