What's the most extreme weather you've been in? A memorable storm? Heat wave? Or something else?

Some years ago - maybe 18 - I was walking with schoolfriends in the Caingorms in Scotland. We were serveral miles out of Aviemore when we were caught in a whiteout while travelling over a mountain pass. We literally couldn't see our hands in front of our faces, the snow was so thick. We formed a train, with each of us holding the rucksack of the person in front, and moved in small circles until we found a bothy we knew was nearby to shelter in. We spent an hour or so there, waiting for the storm to pass.

A frightening, but exhilarating experience.