According to Javanese beliefs, the meaning of an event (and the character of a person born in a given day) can be determined by examining the occurrence of the event according to various turns of the traditional calendar. One common use of this forecast method can be found in the Java birthday system called wetonan.
Your Weton is a combination of seven days a week (Monday, Tuesday, etc.) with five days of Javanese market (Legi, Pahing, Pon, Wage, Kliwon). This rotation repeats every 35 (7 x 5) days, so according to the Java calculations your birthday repeats every five weeks starting from your birth day.