The advice to always keep your coat in the cabin during the winter is a good one, and not just for emergencies. I sometimes used to pack it in the checked luggage so I wouldn't have to carry it. Then there was that one time when they deplaned us in the middle of the tarmac at CDG and we had to wait for 5-10 minutes to be bused to the gate in a blizzard, and I was in short sleeves, lol... (I was connecting from Florida to Greece, and did not anticipate that...)