What is the lowest temperature suitable for wearing shorts outside?

Last winter I was glad to see others wearing shorts also in the dead of winter....

 

At 66 that metric's much different than it was when I was 16.

This time of year, do you know how to tell a native Floridian from a Canadian?
At the beach, Canadians are the ones wearing bikinis, and Floridians are the ones wearing arctic parkas.

 

Seems every winter, even on the coldest days, I see more and more college kids who will wear something like a hoodie, covering up hands or curling up as they walk but then have shorts or a skirt on. I'll never understand it at all. When I ask any of my tenants why they do that, they're alway's "my legs dont' get cold". yeah okay, guess you're not out in it long enough.

 

I live in Texas, so it's hot like 10 months out of 12, but I see people wearing shorts even when it drops into the 30s in winter. I just don't get it.