Today (July 15th) is St Swithun's Day and according to English folklore if it rains today we'll be stuck with rain for the next 40 days!
As the old proverb says:
St Swithun's day if thou dost rain
For forty days it will remain
St Swithun's Day if thou be fair
For forty days 'twill rain nae mare
So who was St Swithun, and how can his feast day have such a dramatic effect on the British summer?
Born sometime around 800 AD, Swithun was consecrated Anglo-Saxon Bishop of Winchester in October 853 and held the office until his death, probably in 862. Although certainly a Godly man who built many new churches, restored others and was good to the poor, little was written about Swithun during his lifetime. He is better known for his reputation for miracle working long after his death.
One thing that is recorded is that on his deathbed he begged to be buried outside the north wall of his cathedral, where passers-by would walk over his grave and the raindrops from the eaves would fall upon it. His wishes were met, but in 971 – more than a century after his death – the decision was made to open his grave and move his remains to a new indoor shrine within the cathedral.
On the day of the move there was a heavy downpour of rain, taken by some as evidence of Saint Swithun expressing his displeasure at those going against his wishes. That could be the origin of the proverb, though there are other versions, including that it was a pagan tradition only attributed to St Swithun's feast day as Christianity absorbed many of the old ways into the new religion.
There is also a meteorological explanation to the legend of St Swithun's Day. Around the middle of July the jet stream settles into a pattern which, in most years, will hold reasonably steady until around the end of August. If the jet stream settles to the north of Britain, then continental high pressure is able to move in, bringing warm, sunny and largely dry weather. But if it settles to the south of Britain, then Arctic air and low pressure Atlantic weather systems will prevail, bringing colder, wetter weather.
It is easy to see how our ancestors, whose lives were ruled by the weather much more than ours, might begin to recognise these annual weather patterns and link their start with St Swithun's Day, on July 15th.
However, the proverb is by no means always true. In 1924 London enjoyed 13.5 hours of bright sunshine on St Swithun's Day, followed by heavy rain on 30 of the next 40 days. Conversely, in 1913 there was a 15-hour rainstorm on St Swithun's Day, followed by 30 dry days out of the next 40.
As for St Swithun, he is commemorated by many churches dedicated to him in southern England, and Stavanger Cathedral, in Norway. There is also a St Swithin's Lane in the City of London, St Swithun's School for Girls in Winchester and St Swithun's quadrangle in Magdalen College, Oxford. Finally, fans of the hit 1954 British comedy film "Doctor in the House" and its six sequels might recall that they were set in and around the fictitious St Swithin's Hospital.