Have to concur with what a few have already mentioned, the Bob Booker Mansfield away game in 1989, it were f***ing brass monkeys that neet. Freezing temperatures, biting wind, snow, sleet, had it all. Stood on the terrace in front of the stand first half, second half went behind the goal, which was actually not as cold. Booker was brilliant that night and changed a few fans impression of him (me included). I joined in the pitch invasion at the end and went flying on the snow/sleet covered pitch (partly due to the non-grip slip-on shoes I was wearing, all the rage in the 80s!), only reason I didn't end up on my arse was that I crashed into Deano!
Other 'honourable' mentions for Newcastle away season after, made worse by a 2 hour journey there with the bus having no heating. Sunderland away in late 1995, the one Brownie mentioned, was another brass monkeys afternoon, freezing temperatures, freezing wind blowing off the north sea, sleet, snow, dire Blades performance, rabid Mackems, welcome to Joker Park! Only plus, I was at Sunderland Uni at the time and back home in student digs within 5 minutes of the final whistle.