I don't understand it either. Talking about jackets when being over 20ºC is just madness. I can't even wear cotton or linen ones without overheating and sweating like a pig.I couldn't even think about wearing leather at 20 C (68 F) unless I was on my motorcycle. I would be sweating like crazy. And at 30 C (86 F), I would have heat exhaustion. You guys just have a different constitution from mine.