Are Northerners really tougher than Southerners?

At this time of year in SW Florida we see our guests from the northern states and Canada roaming the streets and beaches in shorts and light tank tops. This morning, it was only 56 F. and I was sensibly wearing a fleece-lined hoody but there were dozens of people on the street in short shorts, flip flops and tanks. I realize 56 degrees feels warmer than 26 degrees but I was really shivering before I put on the hoody. Now its nearly 70 but I still need a light sweater. Is the feeling of warm or cold just in their heads and mine? Or do Northerners bodies develop some kind of insulating fat or something that keeps them warm in cold temperatures?