Based on the decision by the Saudi Arabia’s Supreme Court yesterday, 1 Dhul-Hijjah 1439 AH starts on Sunday, 12 August 2018. It seems this decision was made based on the Ummul Qura Calendar used there for civil purposes and not based on rukyatul hilal or moon sighting report. There was no mention of moon sighting report in the news propagated by the Saudi Pers Agency (in English version) regarding the start of 1 Dhul-Hijjah 1439 AH. However, in the arabic version of the pers-release, there was mention that the decision was based on the sighting of the crescent moon of Dhul-Hijjah on Saturday evening in the region.
It must be noted that based on Crescent Moon Visibility Map for 1 Dhul-Hijjah 1439 AH, there is no chance of naked-eye moon sighting in Saudi Arabia on Saturday evening. The moon is only about 1.7 degrees above horizon when the sun set in Makkah on Saturday and it stayed for only about 15 minutes. Saudi is well known for such ‘crescent moon sighting’ when scientifically it is impossible to see the moon by naked eye.
Therefore, the culmination of Hajj in Saudi Arabia, the Wukuf in Arafah, 9 Dhul-Hijjah 1439 AH will be on Monday, 20 August 2018 and Eid-ul-Adha 1439 AH there will be on Tuesday, 21 August 2018.