It's been a long time since New York City has had a white Christmas. Like most Americans dreaming of a white Christmas, there's no chance of one in the city this year. The National Weather Service says Central Park has not had snow on the ground on ...

First, let's define our terms: according to the National Weather Service, a white Christmas happens when there is one inch or more of snow on the ground on the morning of the holiday.

It need not snow Dec. 25 to fit the Weather Service's definition of a white Christmas: There just needs to be at least one inch of snow on the ground. A trace amount of snow also does not count. On average, about 38% of the Lower 48 has an inch of snow on the ground on Christmas Day, according to 21 years of data compiled by NOAA.