The month of Hajj 2018, islamic hijri month of Dhul-hijjah 1439 AH, is marked by the birth of the moon on Saturday, 11 August 2018 at 09:57 UT. In the evening of this day, the crescent moon (hilaal) of Dhul-hijjah 1439 would not be visible by naked eye from almost everywhere in the world.
The crescent moon of Dhul-hijjah 1439 AH would be easily visible on the evening of the next day, Sunday, 12 August 2018. Therefore, 1 Dhul-hijja 1439 AH starts on Monday, 13 August 2018.
It is also very likely that Saudi Arabia, where the pilgrimage, Hajj, takes place would also start 1 Dhul-hijjah 1439 AH on Monday, 13 August 2018. This is because Saudi usually rely upon ‘moon sighting’ to start the Dhul-hijja and the chance to see the crescent moon would be almost impossible on Saturday evening. See the “Crescent Moon Visibility Map of Dhul-hijja 1439 AH” above!
As a result, the Wukuf in Arafah, the culmination of Hajj ritual, on 9 Dhul-hijja 1439 AH will fall on Tuesday, 21 August 2018 and the Eid-ul-Adha, the Eid of Sacrifice, on 10 Dhul-hijja 1439 AH will be on Wednesday, 22 August 2018.