Thousands of people have been forced to evacuate the coast of Florida after the subtropical Storm Alberto gained the early jump on the 2018 hurricane season.
Alberto, which is the first named storm of the year, is anticipated to make landfall on the northern Gulf Coast.
The National Hurricane Centre in Miami said it was maintaining its strength as it approached the Florida panhandle and was centred about 100 miles (165 kilometers) south-southeast of Destin.
The storm had maximum sustained winds of 65 mph (100 kph) and was moving north at 6 mph (9 kph).
"On the forecast track, the centre of Alberto will move over the northern Gulf of Mexico overnight and cross the northern Gulf Coast in the warning area on Monday," the National Hurricane Centre said.
It warned of life-threatening surf conditions, the possibility of a few brief tornadoes in much of Florida and parts of Georgia, South Carolina and Alabama. And, it said, heavy rains are also expected in many areas.
Lifeguards posted red flags along Pensacola Beach, where swimming and wading were banned amid high surf and dangerous conditions.
Gusty showers were to begin lashing parts of Florida on Sunday, and authorities were warning of the possibility of flash flooding.
The hurricane centre said a tropical storm warning was in effect from the Suwannee River in Florida to the Mississippi-Alabama state line.
Agencies contributed to this report
