Science of St. Swithun's Day

Have ewe heard about the folklore of St. Swithun’s Day? The legend says that on 15th July, St. Swithun’s Day, if it rains then it will continue to rain for a further 40 days. For a Cumbrian this is known as “Monday”.

St. Swithun’s Day is nearly here, but do ewe know the origin of this mystical day?

St. Swithun: The Myth, The Legend

St. Swithun was a Bishop—specifically the Bishop of Winchester ordained by King Æthelwulf of Wessex—probably born around 800 AD. It’s not really known where his name comes from, but a good guess might be from the Old English word swiþ, meaning “strong”.

Though he became more known for his miracles, during life he was famous for his piety as well as his devotion to building new, or restoring old, churches. When he gave banquets, he invited the poor and not the rich. Sounds like a stand up fella to us!

The Miracles of St. Swithun

St. Swithun was made famous for his “Winchester egg-woman” miracle. This isn’t about a woman who turns into an egg, or a lady who was half-woman, half-egg… the story goes that an old lady’s eggs had been smashed by workmen building a church. Swithun picked the broken eggs up and, it is said, they miraculously became whole again. Hooray!

A stained glass depiction of St. Swithun

His second miracle, occurring after his death, is what gave rise to the now famous folklore. On his deathbed he pleaded that his body be buried outside by the north wall of his cathedral, so that he’d be trodden and rained on, ever the humble man. But more than 100 years later, on July 15th, the monks at Winchester moved St. Swithun’s remains to an elaborate shrine inside the cathedral, to be venerated by pilgrims.

The spirit of St. Swithun wasn’t happy with this, though, and expressed his displeasure with ferocious and violent rainstorms that lasted 40 days and nights. And thus, the legend was born.

St. Swithun's Day: Folklore or Science?

The proverb about weather attributed to St. Swithun goes:

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

There is actually some scientific truth behind St. Swithun’s Day.

Around the beginning to middle of July, the jet stream settles into a pattern which, in about 7–8 out of 10 cases, seems consistent until the end of August. When the jet stream lies north of the British Isles then continental high pressure, and lovely weather, is able to move in; when it lies across or south of the British Isles, Arctic air and Atlantic weather systems (cold and wet weather) predominate.

According to the Guinness Book of Records there have been two predictions that were seriously wrong:

  • on July 15th 1924 there were 13.5 hours of sunshine recorded in London, which were then followed by 30 of the next 40 days being wet, and;
  • on July 15th 1913 when a 15-hour rainstorm was followed by 30 dry days of 40.

Alternatively, if you’re Cumbrian, instead of forty straight days of rain you might just end of up with 15 trillion litres of rainfall (more than a month’s worth) in a single day. Thanks, Storm Desmond.

Speaking of rain in Cumbria, did ewe know that the County holds two UK rain records?

  • The most amount of rain in 24 hours (341.1mm at Honister Pass during Storm Desmond, 5th December 2015), and;
  • the wettest inhabited place in the UK (Seathwaite, annual average rainfall of 3,304mm compared to UK average 1,154mm).

When it comes to wet weather, us Cumbrians at Herdy know what we’re talking about: that’s why you can trust our delightful range of Herdy umbrellas.

How do ewe deal with the rain? Have a chat with us in the comments or join the flock on our Facebook, Twitter, Instagram, or email us.

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