“If you wanted the weather to change from cloudy and rainy to sunny and dry: break an egg over a wall under the moon in honor of Saint Clara and the weather would change in the morning.”

This is my informant’s synopsis of a superstition her grandmother held.  My informant is a native of Brazil and is of Portuguese descent.  According to her, her grandmother, from whom she learned this superstition, was a fervent Catholic and “knew hundreds of saints and their miracles and for every misfortune or mishappen there would be some saint to pray to or a superstition to fix it!”  She said superstitions were her grandmother’s specialty.
This belief strikes me as one of the most contrived-sounding superstitions I have ever heard; it really seems strange to combine all those elements.  According to the New Advent’s Catholic Encyclopedia (http://www.newadvent.org/cathen/index.html), there were two St. Clare’s (but no “Clara”).  Both were known for their piety, but neither is associated with the weather or the sun or clouds or rain.  Certainly, neither is associated with the egg or fertility, as nuns are celibate.  This magic- superstition is likely an example of hybridization.  As many holidays including Christmas and Easter were once non-Christian feasts, to which the Catholic church attached Christian meaning to facilitate mass-conversion within their growing dominion, this superstition was probably once a native idea, to which Portuguese Catholics attached Saint Clara (or Clare).  As the name “Clare” (and also “clarity” and “clairvoyance”) is associated with light, St. Clare was probably chosen to replace a pagan entity that manipulated weather in the native lore.