A colloquial expression, used to denote icy weather.
'Freezing temperatures' isn't really an idiomatic expression at all and you might think that it is literal it is self-explanatory. That's true, but I've included it here, not because it needs explaining, but because I enjoy the occasional run round on my favourite hobby horse.
The recent (January 2010) cold weather in the United Kingdom has brought the population here into virtually continuous earshot of the inexact expression 'freezing temperatures'. News and weather reports aren't considered complete without it; for example, the BBC News website, January 2010:
"UK-wide severe weather warnings of ice are in place amid freezing temperatures."
That's my cue to throw pieces of cold turkey, needleless Christmas trees and anything else at hand at the television. 'Freezing temperatures' makes no sense! There, I feel better now. Material objects can be cold, chilly or even freezing, but temperatures can't, any more than they can be purple, undercooked or frightened of ghosts. Temperature, like price and speed, is a numerical measure.
I know this is a degree of pedantry that few will subscribe to and that the horses of freezing temperature, cheap prices and fast speeds have well and truly bolted, but that won't stop me limping after them on my trusty old hobby horse. It gets worse; when people speak of a freezing temperature, what they really mean is a temperature low enough for water to freeze. So, pushing the horse to its limits, even 'freezing weather' is only really appropriate for sub-zero temperatures - most often, when people say 'it's freezing' in here', it isn't.