Friday the 13th is often considered by those who believe in superstition to be a day of bad luck. The fear of Friday the 13th is called paraskavedekatriaphobia. It is a form of triskaidekaphobia, fear of the number thirteen.
The following months have a Friday the 13th:
Because the Gregorian Calendar 400-year cycle has a whole number of weeks, it is not possible for exactly 1 in 7 months to have a Friday the 13th. In fact, the 13th is more likely to be a Friday than any other day of the week.
The months of Friday 13th are determined by the Dominical letter of the year