Parts of Florida face “unsurvivable” conditions when Hurricane Helene hits later on Thursday, the US weather service said, warning that howling wind will drive destructive waves and storm surge as high as 20ft (six metres) on to the low-lying coast.
Residents fled ahead of the incoming hurricane amid mass evacuation orders.
The fast-moving storm was a Category 2 on Thursday morning, the National Hurricane Centre (NHC) in Miami said, packing wind speeds of 105 miles (169km) an hour as it churns over the warm waters of the Gulf of Mexico.
The NHC said Helene – which it described as one of the largest Gulf hurricanes in recent decades – is expected to make landfall at or near Florida’s Big Bend coast in the evening and could develop into a Category 3 or 4.