A white Christmas means that at least an inch of snow has fallen on Christmas Morning .
In most countries , it simply means that the ground is covered by snow at Christmas , but some countries have more strict definitions . In the United States , the official definition of a white Christmas is that there has to be a snow depth of at least 1 i on Christmas morning , and in Canada the official definition is that there has to be more than 2 c on the ground on Christmas Day .