Is there an accepted definition of a White Christmas? What if snows, but doesn’t stick? What if snows last week, but hangs around past Christmas? And, does it have to snow on Christmas Eve, or could it be Christmas Day, or the night of the 25th? I’m not sure if there may be a factual answer or not, so Moderators, feel free to move to IMHO if need be! (I can take it!) - Jinx
I think a white Christmas is defined when a certain amount (measured in mm, inches) of snow settles on the ground. I’m not sure if there is any concensus on exactly what level makes a white Christmas, though I do know both the Royal and American Meteorological Societies have offical levels for white Christmases.
In the South it counts if you see a few snowflakes. I actually made photographs of a little dab of snow on the ground.
According to the National Oceanic and Atmospheric Administration’s National Climatic Data Center it is an inch of snow on the ground.
But of course, if it is snowing, some people would consider that a White Christmas, even if it doesn’t stick! I think the NCDC has it pretty much right. It doesn’t matter whether or not the snow fell on the 23rd or the 25th, if there is an inch on the ground, it is a White Christmas.
(but of course this is soon to be shuttled off to IMHO 
)
I thought it was all about caucasians. Silly me.
The definition in the UK believe it or not is that one flake of snow has to fall on the weather centre roof in London - thats the definition by which the bookmakers pay or dont on bets.
I believe that you can now bet on other cities as well, but London was always the standard.
Heres a link that gives some more detail
http://news.bbc.co.uk/1/hi/uk/1717397.stm
It is a white Christmas if there is enough snow on the ground to track a cat. That might only be true in Wisconsin though.
It’s a white Christmas if there’s enough shave ice for the whole family. That might only be true in Hawaii though 
Its a white Christmas if the egg you throw on the ground fries and becomes white 
Well at least it is here.
I thought the song pretty much spelled it out.
One inch of snowfall at sunrise is how I have always heard of it while listening to meteorologists.
I don’t know about the official definition, but if I look out the window on Christmas morning and the ground is white, then it’s a white Christmas. If the ground is dead-grass yellow, then it isn’t a white Christmas.
I’m sure any definition is always arbitrary. That said, the Canadian meterologists (in The Toronto Globe and Mail) recently defined a “white Christmas” as one with 2 cm of snow on the ground and an “ideal Christmas” as a White Christmas where it is also currently snowing.
According to Tom Skilling on WGN in Chicago, we have a white christmas if the official amount of snow is 1", which means at O’Hare airport. Seems a little too pedantic to me though.
I think a “White Christmas” was what was promised to all Americans if they elected Strom Thurmond in November 1948.