Too many years ago for any one to know about, the FedEx guy who came to the small travel agency where I worked in St. Louis was never, ever, seen in anything other than shorts as well as a short-sleeve shirt! We always told him that he'd freeze to death (especially when we were bundled up against near-zero temps. He shrugged it off!
Perhaps there's some truth that those who are exposed "24/7" to the cold will come to ignore it!
But, when I head out in my golf cart and the temperature is below 50F, I'm likely to be wearing a fleece jacket, hat and gloves!
With the curtains down, too!
SWR