St Swithin (d. 862), English ecclesiastic. He was bishop of Winchester from 852. The tradition that if it rains on St Swithin's Day it will do so for the next forty days may have its origin in the heavy rain said to have occurred when his relics were to be transferred to a shrine in Winchester cathedral. His feast day is 15 July.
Saint Swithin's day, if thou be fair, for forty days it will remain; Saint Swithin's day, if thou bring rain, for forty days it will remain traditional weather rhyme, early 17th century; Saint Swithin was a bishop of Winchester who died in 862, and his feast day is 15 July.

Swithin, Saint (d.862) Anglo-Saxon bishop of Winchester (852–62). Details of his life are sketchy, it is known that he was an adviser to the West Saxon kings Egbert and Ethelwulf. His feast day is July 15. According to superstition, the weather on St Swithin's Day will last for the next 40 days.