For many people Friday 13th is a day to fear as it
means bad luck for them. Although there’s no proof
why that is, it’s proven that bad things do not happen
more often at this special date constellation.

This phenomenon, called paraskevidekatriaphobia, describes a special phobia to Fridays and the number thirteen.

If you are afraid of Friday 13th or superstitious, this info on Wikipedia might help you organize yourself through the year and avoid planning stuff on friday 13th of the corresponding year with some side info where this superstition comes from:

Read Wikipedia article