It's official; winter has not yet started


Of course, you will have noticed as you said your matins that today, November 23rd, is the feast day of St Clement, and according to an ancient mediaeval formula: "Dat Clemens hiemem, dat Petrus ver Cathedratus, aesuat Urbanus, et autumnat Bartholomaeus". Translated into the civil calendar, this useful aide-memoire asserts that winter starts on St Clement's Day and continues until February 21st; spring begins on St Peter's feast day and lasts until St Urban's Day on May 25th; and summer is the period from then until St Bartholomew's Day in late August, from which time autumn lasts until St Clement's feast day comes around again.

The whole thing, however, has really very little to do with saintly interest in the weather. Clement was the fourth Pope and the patron saint of tanners, and like many of his ilk in those days, he came to a very nasty end: he is said to have been martyred around AD100 by being thrown into the sea tied to an anchor. The ecclesiastical authorities, moreover, are silent on the important question of the saint's personal interest in the science of meteorology, but he has earned a footnote in its annals by virtue of the fact that it was widely believed in days gone by that winter began on Clement's feast day.

As it happens, if you examine carefully the average weather patterns in these islands, it is possible to find some meteorological justification for this notion, although 1998 is not a good example. It is common in late autumn for a spell of quiet settled anti-cyclonic weather to occur, that which we would nowadays call an Indian Summer. But the settled spell must end. And it often happens that this reversion to the cool, blustery, rather wet conditions brought about by the return of the North Atlantic depressions to our shores takes place around the third week in November, in fact around St Clement's Day.

Meteorologists define the winter season by the average temperature. If temperatures in the northern hemisphere are averaged over the years, the coldest time turns out to be mid-January, so it seems sensible to define "winter" as the quarter of the year centred on this period. Indeed by this definition, choosing St Clement's Day as its beginning is not far out at all. It is thought best by meteorologists, however, to stick to calendar months for these purposes, since everyday life tends to be organised around the traditional monthly calendar. This leaves us with a winter comprising the months of December, January and February, and by that reckoning, the season will begin a week tomorrow.