The tune crooned by Bing Crosby is still one of the most popular Christmas songs of all time. It's endured as a favorite — despite a complicated and controversial history.

A “white Christmas” is defined by meteorologists as having at least one inch of snow on the ground Christmas morning.

Statistically, the chance of a white Christmas in the Poconos is 40%. But then it really drops as you head to the south -- Lehigh Valley. 90%, Trenton 12%. Philadelphia, Wilmington, and the Jersey Shore, all less than 10%. And this year, it's even less than that because temperatures will be at or above average from Christmas Eve through the 28th.

Kansas City has had only 27 white Christmases in its history, according to data that goes back to 1893 from The Weather Channel. The 30-year average, which resets every 10 years, shows that chance for snow is between 20% and 25%.

A powerful Pineapple Express storm could end up delivering a wet, white and potentially wild Christmas to California, with the possibility of snow in the Sierra and plenty of rainfall across the Southland.

So imagine the excitement when 3.6 inches of snow fell from Christmas Eve through Christmas Day 1987 in Tucson, Arizona, the city's only white Christmas on record. Prior to that, there had been only 14 days in the city's history since 1894 that had an inch of snow on the ground.