White Christmas

A white Christmas means that at least an inch of snow has fallen on Christmas Morning. This is more common in some countries than in others. 
For example, in the United Kingdom, there are not a lot of White Christmases; but in Canada, there is almost always a White Christmas. Ireland's last "official" White Christmas was in 2004.
White Christmases in the United States.
Since the 1950's, there are less White Christmases in the USA.