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
It’s the Feast Day of St Swithin’s Day today, 15 July. At the time of his death (on 2 July 862) he was Bishop of Winchester. The legend goes that Swithin desired to be buried outside Winchester Cathedral, and he was. However, about a century later he was reinterred inside; well mostly, for various bits of his mortal remains were buried elsewhere. He supposedly showed his displeasure at being buried inside; there was heavy rainfall, hence the saying. But of course, it might have been a coincidence, and the saying is apparently later than the time of his reinterment.
It hasn’t rained here today—so far.