Posted by: Didapper PJ11 JUL 2012
AFTER weeks of wet weather we have nearly reached St Swithun’s Day (15 July). According to weather lore, if rain occurs on St Swithun’s Day, it will be followed by a further forty rainy days.
Swithun (or Swithin) was bishop of Winchester from 852 until his death in 862. His 15 July feast day commemorates the date in 891 when his remains were removed from an almost forgotten outdoor grave into the city’s newly restored cathedral.
According to contemporary writers, many miracles occurred around the time of the move, and attempts have been made to link summer weather patterns directly to him. One legend says that he posthumously caused rain because he was miffed at his remains being moved indoors.
However, the weather lore almost certainly relates not to the man himself but to his feast day. And there is a scientific basis for this. In mid-July the northern polar jet stream usually settles into a pattern that remains fairly steady until late August. If its track passes to the north of Britain then continental high pressure moves in, leading to hot, dry weather. But when it lies across Britain or passes further south — as it has done so far this miserable summer — then Arctic air and Atlantic weather systems hold sway, leading to lower temperatures and frequent rain.
Since British weather records began, no wet St Swithun’s day has ever been followed by 40 more damp days, although on occasions the number has approached 30. But perhaps “forty” should not be taken literally, since in early Jewish, Christian and Islamic tradition the word was long used to mean a vague “many” rather than a precise two score.
Religious texts contain numerous examples of “forty” seemingly used in this way. One of the best known of these is also weather-related — the forty days and forty nights of rain that preceded the Biblical flood. Sadly, the Bible does not record whether the deluge began on 15 July.