[Bm] It could be Fahrenheit, which seems to be ubiquitous in the USA apart from within scientific communities. IIRC, -5F is pretty damn cold, that is (does a quick calculation) -20.5 recurring. Brrrrrrr.
Funny thing, this differing scales of temperature malarkey. Last night, in the quiz - one of the questions was "At what temperature do both Centigrade and Fahrenheit read the same?" Could I get my head around that? Could I b*ggery.
Gusset - I'm SO pleased you like my name for you. I'm equally gratified that you haven't transposed the two words :-)