2 of the coldest of the 60's I know of were the 63 NFC Championship Game and the Ice Bowl.
1 thing I've noticed was the low scoring of both games.
The Bears won the 63 game by only 14 points
and Green Bay while maybe wasn't all that low scoring, think the packers won by 20 points though naturally they remained under that number for most of the game.
I wonder if the extreme cold might of played a part in both games being the way they were?
They were even considering postponing the Ice Bowl.