According to a report in Saudi media, Hajj Minister Tawfiq al-Rabiah has requested that pilgrims refrain from leaving their tents between 10:00 am and 4:00 pm on Thursday.

The "Day of Arafat" traditionally marks the high point of the hajj, when pilgrims scale Mount Arafat on the outskirts of Mecca.

There, pilgrims assemble on the 70-metre (230-foot) high hill and its surrounding plain for hours of prayer and Koran recital, staying there until the evening.

There is little to no shade on Mount Arafat, leaving pilgrims directly exposed to the harsh desert sun for hours.

"We warn against climbing mountains or high places on the Day of Arafat, as it causes extreme physical exertion and increases the risk of heat exhaustion," the health ministry said in a separate statement published by Saudi media.

Temperatures this year are forecast to exceed 40 degrees Celsius as one of the world's largest annual religious gatherings, bringing together devotees from around the globe, gets under way on Wednesday.

Officials have beefed up heat mitigation measures hoping to avoid a repeat of last year's hajj, which saw 1,301 pilgrims die as temperatures reached 51.8 degrees Celsius (125.2 Fahrenheit).

This year, authorities have mobilised more than 40 government agencies and 250,000 officials, doubling their efforts against heat-related illness following the lethal heatwave of 2024.

Shaded areas have been expanded by 50,000 square metres (12 acres), thousands more medics will be on standby, and more than 400 cooling units will be deployed, the hajj minister told AFP last week.

As of Sunday, more than 1.4 million pilgrims had arrived in Saudi Arabia for the pilgrimage, officials said.