This year’s Hajj pilgrimage to Mecca coincided with a severe heat wave, and numerous pilgrims lost their lives.

During this year’s Hajj pilgrimage in Saudi Arabia, more than a thousand people died in the extreme heat. Unofficially registered pilgrims who took part in the rituals in temperatures of up to 51.8 degrees accounted for more than half of the deaths, according to a count by the AFP news agency. According to an Arab diplomat, 658 of the dead were from Egypt, 630 of whom were not officially registered.

Ten countries have so far reported 1,081 deaths during this year’s Hajj. The figures come from official statements or from diplomats of the respective countries.

The period of the pilgrimage is determined by the Islamic calendar and has repeatedly coincided with heat waves in recent years. Earlier this week, temperatures of up to 51.8 degrees were recorded at the Great Mosque in Mecca.

The five-day major event in Saudi Arabia is one of the five pillars of Islam and should be undertaken by every healthy Muslim who can afford it at least once in their life. For financial reasons, many believers take part in the Hajj without an official pilgrimage license and are therefore not registered by the Saudi Arabian authorities.

In the run-up to the Hajj, the Saudi Arabian authorities said they had expelled hundreds of thousands of unregistered pilgrims from Mecca – many of whom, however, apparently still took part in the Hajj, which began last Friday.

These unregistered pilgrims were particularly exposed to the extreme heat. Without a licence, they were denied access to refrigerated rooms set up by the authorities for the 1.8 million authorised pilgrims to recover from hours of walking and praying in the open air.

“People were tired after being dispersed by security forces ahead of Arafat Day. They were exhausted,” an Arab diplomat told AFP on Thursday, referring to last Saturday, when believers climbed Mount Arafat in scorching heat to pray for many hours. He said heat was the main cause of death among the Egyptian pilgrims who died, causing complications related to high blood pressure and other problems.

In addition to Egypt, Malaysia, Pakistan, India, Jordan, Iran, Iraq, Tunisia, Indonesia and Senegal also reported deaths during the Hajj, although in many cases the authorities did not specify the exact cause of death.

According to official figures, 1.8 million believers took part in the Hajj this year, including 1.6 million pilgrims from abroad.

Many of the rituals are performed outdoors and on foot, which is particularly challenging for older people. According to the Saudi Arabian authorities, more than 2,700 cases of heat-related exhaustion were recorded on Sunday alone. The authorities did not comment on deaths caused by the high temperatures.

According to a Saudi Arabian study published in May, weather conditions during the Hajj are becoming increasingly difficult due to global warming: the average temperature during the pilgrimage rises by 0.4 degrees every decade.