More than 1.5 million Muslim pilgrims gathered on Mount Arafat on Tuesday for the spiritual climax of the annual Hajj pilgrimage, enduring soaring desert temperatures as they offered prayers and recited verses from the Quran.

From early morning, vast crowds dressed in white filled the plains and rocky hill of Arafat near Makkah, where Prophet Muhammad is believed to have delivered his final sermon around 1,400 years ago.

Temperatures climbed close to 40 degrees Celsius during the day, following several days of extreme heat in Makkah that touched 44°C. Saudi authorities repeatedly urged pilgrims to stay hydrated, avoid prolonged exposure to the sun, and use umbrellas during the largely outdoor rituals.

The Hajj pilgrimage, one of the five pillars of Islam, is mandatory once in a lifetime for Muslims who are physically and financially able to undertake the journey.

This year’s pilgrimage is taking place against the backdrop of heightened tensions in the Middle East following the conflict involving the United States, Israel, and Iran. Despite the regional unrest, Saudi officials said international pilgrim numbers were higher than last year.

More than 30,000 Iranian pilgrims arrived for Hajj this year, significantly lower than the 86,000 initially expected. Iran’s state-run IRNA news agency attributed the decline to the ongoing “wartime situation” in the region.

Many male pilgrims, prohibited from covering their heads during the state of ihram, carried umbrellas to shield themselves from the blistering sun as they climbed and prayed on Mount Arafat.

After sunset, pilgrims will travel to Muzdalifah, where they will spend the night collecting pebbles for the symbolic “stoning of the devil” ritual in Mina, which begins on Wednesday.

The Hajj rituals are believed to retrace the path of Prophet Muhammad’s final pilgrimage and remain among the largest annual religious gatherings in the world.