July 15 marks St Swithin’s Day, a day often forgotten about unless you are a fan of the book, movie or Netflix series One Day.

Despite dating back hundreds of years, the day has only become popularly marked in recent times thanks to its heavy mention in the David Nicholls book.

Those who are aware of One Day will know that the day is based on old folklore believed to date back hundreds of years ago and it can have a big impact on British summer.

What is St Swithin’s Day?

St Swithin’s Day has an important link to summer, with the belief that if it rains on July 15, it will then rain for the next 40 days.

However, if it’s a dry day, you can expect 40 days of summer weather with no rain.

St Swithin has links to the bishop of Winchester St Swithin who asked to be buried in the churchyard where rain and the steps of passersby might fall on his grace.

According to Britannica, his body was moved into the cathedral on July 15 when a storm took place.

How is St Swithin’s Day linked to One Day?

Nicholls book One Day tells the story of friends Dexter and Emma who meet ever year on or around the time of St Swithin’s Day across several decades.

Every year they meet on St Swithin’s Day and it doesn’t rain, symbolising that the two have each other and that the next 40 days will be clear of rain.

One Day uses St Swithin’s as a way to express the relationship between Dexter and Emma, throughout their friendship, love and missed opportunities.

What is the St Swithin’s Day poem?

The poem that sums up St Swithin’s Day and is recited by Dexter in One Day is as follows:

"St Swithin's Day, if it does rain

Full forty days, it will remain

St Swithin's Day, if it be fair

For forty days, t'will rain no more"

Will it rain on St Swithin’s Day 2024?

If you’re hoping for a dry summer, then look away. The Met Office has issued that heavy rain and possible thunderstorms have been forecast for parts of the UK.

The Met Office warned “torrential downpours” are likely, with 15-20mm of rainfall forecast in less than an hour in some places – and 30-40mm within three hours in others.

This may be accompanied by lightning throughout the day, the forecaster added.

There is a small chance some homes could be flooded or see power cuts and fast-flowing or deep floodwater may also cause a danger to life.

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Spray and flooding could lead to difficult driving conditions and road closures, the Met Office said.

There is also a chance some train and bus services will be delayed or cancelled in affected areas.

The heavy rain is expected to spread north across the affected area during the day.