Holidays such as this are determined by moon sightings, although indications are often given well in advance to allow for planning.
In a statement last year, the UAE government explained the process, saying: “The official reference to determine Islamic occasions, such as the beginning of Ramadan or Haj, is the Hijri Calendar. It is based on the phases of the moon. Hence, the exact dates of Islamic events vary from one Gregorian year to another as they depend on the local sightings of the moon."
OTHER ANTICIPATED PUBLIC HOLIDAYS - January 1: New Year's Day - May 5: Israa and Miraj Night - June 6: Ramadan expected to begin - July 6: Eid Al Fitr - September 2: Haj season - September 10: Arafat Day - September 11: Eid Al Adha - October 2: Hijri New Year - November 30: Commemoration Day - December 2 and 3: UAE National Day - December 11: Prophet Mohammed’s Birthday (PBUH)