The announcement was made after KSA's moon-sighting committee met to look for the new moon of marking the start of the lunar month of Dhul Hijjah, the 12th and last month of the Islamic calendar. With the moon not sighted, September 14 is established as the last day of the month of Dhul Qaadah, and September 15 starts off the month of Dhul Hijjah.
The peak of Hajj (Day of Arafat) will be on September 23, 2015, followed by Eid on the day after.