The reason Florida stays warm in the winter is because of predominant tropical easterly winds that occur across central and southern Florida.
Those winds keep warm air brought into Florida which keeps Florida warm during the winter.
Occasionally some parts of Florida do get cold on a few days and few nights out of the year during winter but mostly Florida stays pretty warm.
Florida is a winter destination for a lot of people wanting to escape the cold hard winters where they live.
Then again some people move to Florida for good to get away from cold winters during their retirement.
My uncle who lived in New Jersey moved to Florida last year to get away from all the snow and cold during his retirement because he decided he had enough of the cold and snow.
I may move to Florida myself one day as well as I hate the cold weather.
It's not even winter here year and it's only 43 F today and I have my heat on.