I stopped fighting with the kids (12-13 yr. olds) about wearing coats when we went outside about 5 years ago.
I don't get it, either. I was not "warmer" as a kid. Yesterday, when it was about 13 out, I went to the dentist, near my kid's old HS. While everyone I saw was wearing a jacket, some of them had on what I would consider to be a spring jacket, none had gloves, or hats on as they spilled out of the Starbucks.
And I also don't understand some of the riders and runners I see wearing shorts when it's 50, 40, or 30. Last week I saw 2 runners in my neighborhood in shorts. It was around 25 out and their legs were bright red. While I definitely have developed more of a tolerance for cold, the more I ride, I have to wear tights when it's less than 55, maybe 52. Between 55-65 I can do knee warmers or knickers.