Pearl Harbour - cold (weather). This is one I have heard from a fair few people recently. An example of it would be "It's a bit Pearl Harbour out there!". Meaning - there's a nasty 'nip' in the air! This comes from the well-known surprise attack by Japanese planes on the American port in Hawaii in 1941 (history lesson over). Suggested by Lawrence Gore and by Matt Grimshaw.

Leading to the occasional response of "Yeah, I can't believe that Roosevelt didn't call that one" - An expression obviously referring to the local weather fore-caster based up-on the Roosevelt Administration's fore-knowledge of the impending attack.