I think another factor is to dress for where you're going to or from... nowadays I always dress for the climate of where I am going. However, when I was less used to flying I went from Manchester to Miami in late March. In Manchester it was about 26 F and snowing so I wore winter trousers, a sweater, a jacket etc. Nedless to say in Miami it was 95 F and 100% humidity. Not a mistake to make twice.