I lived on that part of the coast, less than a mile from the ocean. Two years, two winters, drove through an ice storm to initially move down there. The ocean stabilizes temperature, keeps it from getting too cold for long, also keeps it from getting very warm. Where it is stablized depends on how close to shore is the Gulf Stream.
Temperatures will be chilly for at least two months, maybe three. It was regularly cold enough that our heat pump was not adequate, had to go to "emergency heat" which was resistance for us, and quite expensive. You will have to deal with the occasional freeze, sometimes for several days at a time. When winter weather hits the coast, it is seldom snow, more often sleet and freezing rain.
The Atlantic Coast, right on the coast, is RV-able in winter from about southern Delaware on down, but you can't always get close enough to the ocean. It is not the sort of climate most snowbirders seek. I know people from the area who go to South Florida for the winter. Even northeast Florida, Jacksonville to Daytona Beach, gets down to freezing time to time, been there trying to tent camp at Daytona in January.
If I wanted "livable" winter weather on the coast, I would seek the Texas Gulf Coast, which tends to be windy, or the Florida-Alabama-Mississippi Gulf Coast, which tends to be cool and wet, but seldom really cold.