The term "White Christmas", apparently, was quite unknown before Irving Berlin penned the famous song of that name for Bing Crosby in 1941. It was written for the film Holiday Inn, in which Crosby was to star with Fred Astaire, and was first heard in public on Crosby's NBC radio show, The Kraft Music Hall, on December 25th, 1941. It has been a constant feature of the festive season ever since.
The context then, of course, was very much American, and in parts of the US white Christmases are two a penny. In Ireland, however, when snow occurs in any quantity it is much more likely to arrive in January or February than in December. White Christmases here are comparatively rare. Their frequency depends to a large extent on which criteria you care to choose. For example, the average number of days in December on which snow falls varies from about six in the north to a mere one in the south, which suggests prima facie a chance of somewhere between one in five and one in 31.
But the statistics are misleading: a single flake is sufficient for meteorological purposes to constitute a "day with snow" and may be enough, indeed, to win a bet if it should fall at a designated spot within the 24 hours of Christmas Day. But it is a far cry from the pristine landscape conjured up by Bing.
On the other hand, one decent fall of snow may leave the countryside white for a week or more, so perhaps, when totting up white Christmases, one ought to think in terms of the number of December days when snow is already on the ground rather than counting those on which it actually falls.
But snow-covered ground is an even rarer sight than falling snow: a December day with a measurable amount of snow on the ground occurs only once every two or three years in most parts of the country. Although this frequency increases quite significantly on high ground, it still means that a white Christmas in any part of Ireland is a comparatively rare event.
By even the most generous criteria, it is only possible to count 12 Christmases since 1960 when snow fell in Ireland, and on only five of these - 1962, 1964, 1970, 1980 and 1984 - could the snow be described as being widespread. Perhaps the nearest we have come in recent years to a real white Christmas was 35 years ago in 1962, when the snow started on Christmas Day and continued on and off in many parts until New Year's Eve.