The meteorologically interfering habits of St Swithin are widely known: rain on his feastday on July 15th condemns us to rain on each and every one of the following 40 days.
But he is not alone.
In Scotland, for example, St Martin Bullion controls the weather for 40 days from July 4th; the Belgians' rainy saint is Godelieve, whose traditional date is July 27th, while Italy's Swithin is St Bartholomew.
And in France, Benedict, Medard, Protase, and Anne are all credited with Swithinian tendencies - threatening a drenching for 40 days if it rains upon their feastday. Today, March 21st, is one of these - the feast of Benedict.
St Benedict, however, has another claim to fame. He is the patron saint of caves, his expertise, apparently, being based on reports that for many years he lived in one at Subiaco, some 40 miles from Rome. But what an interesting fiefdom lies under his control.
Caves differ in their microclimatology, depending on whether they have many mouths, or just the one. Caves with more than one entrance experience drafts and convection currents, which allow the temperature inside to approach that of the world outside.
A cave with only a single opening, however, behaves differently. If it slopes downwards it forms a drainage pit for cold air, and the temperature inside stays remarkably constant, changing by, perhaps, less than one degree over hundreds or even millions of years.
But caves have an abundance of water, and this, with their calm atmosphere, results in a relative humidity that is nearly always more than 90 per cent. It is this saturation of the air which provides the moisture-laden walls so typical of caves.
The air inside a very deep one-mouthed cavern is prevented from complete stagnation only by a tendency for the cave to "breathe" - an exchange of air with the outside world caused by rapid rises and falls of atmospheric pressure - and this has a connection with the reputed attraction that caves have for lightning strikes.
It has been suggested that sometimes radioactive material extracted from the rocks is deposited by subterranean waters on the walls of many caves, and that this in turn leads to an ionisation of the air inside, so that it contains an abundance of electrically charged particles.
As the cave "breathes out" as a result of the local fall in atmospheric pressure associated with a thunderstorm, the resultant outpouring of ionised air at the cave-mouth provides a preferred path for any impending stroke of lightning - or so some experts on these matters say.