There is an old saying that rain on your wedding day is a lucky omen. The Italians even have a saying for it, “Sposa bagnata, sposa fortunata”, which means that a wet bride is a lucky bride. In the U.S., it is commonly repeated that rain is lucky, although most brides would prefer a dry day and a little less luck!
Rain is also considered to be a good wedding omen in Germany, Sweden, and France. This is possibly because rain is associated with a bountiful harvest, and thus, fertility. Some believe that the rainier the wedding day, the more children the marriage will produce. (So if you get married during a downpour, I guess that you can expects to have triplets!)