I intend to find out more about this miracle. If anyone beats me to it, please comment.
Aleteia, Philip Kosloski: During the 15th century torrential rain fell on the French city of Avignon. The Sorgue and Rhône rivers continued to rise until they flooded the lower part of the city, making it one of the worst floods ever in that region. A group of Franciscan friars were worried that their small church would be destroyed.
Even worse, the Eucharist had been exposed in a monstrance on the altar and was not put away before the flood waters came and the Franciscans escaped. Story is here.