Today, in addition to being the novus ordo feast of St Bonaventure, is the feast of St Swithin, Bishop of Winchester, who died in 862. July 15th is the date of his Translation on the following century into the cathedral there. Because he has asked to be buried outside the building so that the rain could run off the eaves onto his grave he expressed, accruing to legend, his displeasure at being moved inside the cathedral by causing it to rain for the next forty days. Hence the importance pf whether July 15th is wet or dry - whichever it is the folklore asserts it will be for the ensuing forty days. On the continent his feast is July 2nd, the date of his burial.
To mark the feast day Gordon Plumb has posted these stained glass images of St Swithin on the Medieval Religion discussion group:
Oxford, Trinity College, Old Library, East windows, second window, 1a, St Swithin:
Winchester Cathedral, Choir Clerestory, East Window, 1a-2a, St Swithin:
Head of figure:
Winchester, Hospital of St Cross and St Faith, East wall, St Swithin (Head modern):