Scientists have predicted which years could be the most dangerous for worshippers.
Muslims must perform their prayers five times a day in the direction of the qibla, facing the Kaaba, the building at the center of Islam's holiest mosque in the Saudi Arabian city of Mecca.
More than 2.37 million pilgrims—mostly from outside Saudi Arabia—are taking part in the five-day ritual.
The world's 1.8 billion Muslim adherents will celebrate Eid al-Adha this week, marking one of Islam's most important holidays.
Iran's Ayatollah Ali Khamenei said Mecca "belongs to all Muslims," and their security during Hajj was a God-given right that Saudi Arabia fails to uphold.
Two men were arrested for burning Salma al-Sharif's car, but officials said it was an isolated incident.
Saudi Arabia wants to build a futuristic retractable roof over Mecca.
Mounting tensions between Qatar and its neighbors spilled over in June, when Saudi Arabia, Egypt, the United Arab Emirates and Bahrain all cut diplomatic ties with Qatar.
The Kaaba, meaning "cube" in Arabic, has been the center of Islam since the time of Prophet Muhammad, but it was worshipped for centuries prior.
Qatar has accused Saudi Arabia of deliberately making it difficult for its pilgrims to obtain permits to go to Mecca.
Seven of the Boeing 777s will fly Qatari pilgrims from Doha to Jeddah to attend the annual Hajj pilgrimage.
Tens of thousands of social media users are calling for the arrest or execution of a man who filmed himself shooting cats with a rifle in Saudi Arabia.
The move would cost Abdullah the equivalent of $600,000 to fly between 1,200 and 1,600 pilgrims to Jeddah or Medina.
Saudi Arabia's foreign minister says Qatar asked his country to cede control of Islam's two holiest sites, but Qatar denies doing so.
Saudi Arabia called the attack "a desperate attempt by Shiite Houthi rebels to disrupt Hajj."
Iran's defense minister was responding to Saudi comments about the "battle" for influence in the Middle East.
The Houthis said they targeted an international airport 45 miles from Mecca.
Hundreds of Iranians died in a crush during last year's pilgrimage; both countries accuse each other of politicizing the hajj.
The Associated Press puts the dead at 1,399, while the official Saudi estimate is 769.
The Iranian president has warned "the Islamic Republic is prepared to use force."