July 15 marks St. Swithin’s Day, which is very important if you’re concerned about the weather. Brits are being told to look out for one thing, as it could determine what the weather will be like for the next 40 daysJuly 15 marks St. Swithin’s Day, which is very important if you’re concerned about the weather. Brits are being told to look out for one thing, as it could determine what the weather will be like for the next 40 days