If you’re dreaming of a white Christmas anywhere in the United States this year, you’re luckier than last year – despite the forecast for unseasonably warm temperatures on Christmas Day, which could potentially bring more rain and spring-like thunderstorms than snow over the next few days.

The National Weather Service officially considers a location to have a white Christmas if there is already an inch of snow on the ground or if at least an inch of new snow falls on Christmas Day.

The snowpack forecast is produced using the Snow Data Assimilation System, a computer model from the National Operational Hydrologic Remote Sensing Center, operated by the National Oceanic and Atmospheric Administration.

“This year is starting to be an interesting snow season,” said Shawn Carter of the National Weather Service. There is “a pretty good chance,” he said, that overall the country will have more white Christmases this year than last year.

Many areas likely to see snow this year have historically had the highest chance of getting an inch of snow on Christmas.

Atmospheric rivers to the west have already brought snow to some higher elevations in the region and will continue to do so. Snow will also fall in many places in the northern part of the country, including inland in the northeast, where snow amounts will be well above normal. Unfortunately, warmer temperatures this year will make Christmas a wet holiday for many, with rain possible from Texas to Illinois.

Three years ago, NOAA updated the average probabilities for a white Christmas in the United States. Although the report cautioned against comparing the new estimates with those produced a decade earlier, it said that “in more areas the likelihood of a white Christmas has fallen than increased.”

Classic Christmas movies like “Miracle on 34th Street” depict snowfall during the holiday season in New York City, but Central Park hasn’t seen an inch of snow on Christmas in more than a decade.

It’s not the first time the city has gone so long without an inch of snow on Christmas Day. The song “White Christmas” was written during one of those long, snowless Christmas periods.

According to James Kaplan, author of “Irving Berlin: New York Genius,” Irving Berlin appears to have begun writing the song in 1938. That was “when he was spending a lot of time in Hollywood,” Mr. Kaplan said in an interview before Christmas last year.

Mr. Berlin wasn’t particularly happy about being on the West Coast, Mr. Kaplan said, and it’s possible he felt some nostalgia for the old days on the Lower East Side, where he grew up.

According to the National Weather Service, white Christmases were common in New York City at the turn of the 19th century. But when Mr. Berlin wrote the song in the late 1930s, New York City had not experienced a white Christmas since 1930.

First, Mr. Kaplan said, Mr. Berlin wrote an additional verse for the beginning of the song.

It went something like this: “The sun is shining, the grass is green, the orange and palm trees are swaying. There’s never been a day like this in Beverly Hills, LA, but it’s December 24th and I long to be up north.”

But that’s not how the tune was sung by Bing Crosby, who cut the first verse and began with the familiar refrain: “I’m dreaming of a white Christmas, just like the ones I used to know.” Since then, others have uncovered the missing verse and added adding them to their own versions of the song.

Mr. Kaplan said that Mr. Crosby’s recording of the song, as well as the start of World War II, provided “a huge accelerator” to his fame and profitability. “Because Bing Crosby’s recording of the song was heard by soldiers and sailors abroad early in the war,” he said.

The United States entered the war after the attack on Pearl Harbor in December 1941. Mr. Crosby’s recording was released the next year.

According to the Central Park Weather Service, in the years after Mr. Berlin wrote the song, there was no snow at Christmas in New York until 1945, a few months after the end of the war.

With the flakes potentially falling late on Christmas Eve, New Yorkers at least have a chance of escaping the long white Christmas drought. The last time New York City recorded at least an inch of snowfall or snowfall on Christmas Day was in 2009.

Historically, New York City has had a white Christmas only 25 of the last 154 years, about once every six years, according to the National Weather Service.