By December, 1939, the war had begun for England, but it was the "phoney war."

 "In Woolworths," recalls that company's online history,  "customers chose cards, decorations and stocking fillers, much the same as usual. To be sure the tinned peaches and jars of honey sold a bit better than usual as the wisest customers squirreled some away 'just in case', but inside the store you would hardly know the country was at war."  In America, the public was getting the idea via movie reels:

One American travelogue newsreel in summer 1939 visited a Woolworth store in Berlin. A summary of the film remains in the production company's database.

Pan fascia reading 25 und 50 Pfg. Laden F. W. Woolworth Co. GMBH
Voiceover - Woolworths, a familiar sight from home.
Voiceover - Let's take a look at the range on sale
Pan to Adolf Hitler tea tray - 25 pfennigs,
Pan to set of 6 teacups and saucers with swastika pattern - 50 pfennigs.
Pan to window sign.
Voiceover. The sign reads "Our management is not Jewish."
"Jews are not welcome here."

Here is Time's reporting from December 25, 1939.  A year later, Christmas, 1940, all was still pretty serence around the White House though of course Europe had been plunged into darkness and Britain assaulted from the air:

It was a quiet week in the White House. Each night from the tower of Epiphany Church, the bells rang out: Hark! the Herald Angels Sing. At a reception for the members of the Supreme Court the President, cheered after his cruise, cheerfully greeted the Justices. It was quiet compared with the gathering last year, when Frank Murphy, just appointed to the Court, was the lion of the week, and the talk buzzed of the new appointments that had put James Cromwell in Canada and Robert Jackson in the Department of Justice. ..

Last week preparations for Christmas went on as usual. In the east end of the second-floor corridor stood the small family tree, decorated with ornaments handed down via attic trunk from one Christmas to the next. And, as in the past, the President's plans called for the familiar, pleasant ritual of the season—the wishing of Merry Christmas to the members of his office staff, the scene in which the President and his wife receive the members of the White House staff and their children, the lighting of the Christmas tree outside the White House on Christmas Eve, the brief radio message in which the President would speak Christmas greetings to the nation. Each year, after the family dinner on Christmas Eve, the President reads part of Dickens' A Christmas Carol to the young ones and the grownups—taking different selections in different years, but always including the opening scene of Scrooge's cold old countinghouse, always winding up with the flourish of Christmas dinner at the Cratchits and the jubilation of Tiny Tim.

Two years later:

"I'm dreaming of a White Christmas, Just like the ones I used to know  Where the tree tops glisten And children listen to hear sleigh bells in the snow.*

Tailored by Tunesmith Irving Berlin for the suave, sleepy voice of Cinemactor Bing Crosby, this song (from Paramount's Holiday Inn) originally expressed the longing for sleet and ice of an Easterner marooned among the palm trees of Hollywood. But with thousands of U.S. servicemen facing snowless Christmases from North Africa to Guadalcanal, White Christmas has unexpectedly become the first big sentimental song hit of World War II.

Much more detail on Christmas, 1942 here.