Saint Swithin's Day is observed on July 15 and is associated with an English weather prophecy that claims the weather on this day will determine the conditions for the next 40 days. The day encourages individuals to share their local weather forecasts and engage in discussions about meteorology. Common customs include making personal 40-day weather predictions and sharing observations on social media platforms using the hashtag #SaintSwithinsDay. Retailers often capitalize on this day by offering deals on outdoor gear, such as wellington boots and waterproof jackets if it rains, or picnic supplies if the weather is sunny. The legend of Saint Swithin, an Anglo-Saxon bishop, is tied to the day, as it is believed that moving his remains indoors caused a storm that lasted for 40 days. This folklore continues to be a significant part of the cultural celebrations surrounding the day in the U.K.