I know LOTS about werewolves but very little about astronomy but apparently...
'A full moon coinciding on Friday the 13th is not all that uncommon, occurring every three or so years.
But having the combination of a honey moon and Friday the 13th is rare, last occurring on June 13, 1919, according to the popular astronomy site Universe Today. We'll have to wait until June 13, 2098, for the next one.'
(thank you National Geographic)
(illustration from 'Making Monsters Happy' by Susan Gates)