A New Study Reveals Climate Change Is Rapidly Making the Hajj Pilgrimage More Dangerous

“Temperatures recorded in May in Mecca are now typical of summer in the 1980s as climate change shrinks the safe window for the Hajj,” the researchers noted . The study also concludes that climate change “is extending the duration of extreme heat in Mecca into historically cooler months,” eroding the traditional respite that pilgrims once relied on .

The 2026 Pilgrimage: Heat Arrives Even in May

This year’s Hajj, which took place in late May, saw temperatures again exceed 40°C . While that is lower than the catastrophic highs of June 2024, it is further evidence that escaping dangerous heat is becoming harder. The Hajj’s timing in the Gregorian calendar moves back by about 11 days each year . In 2027, it will fall in mid-May . This migration toward winter offers a temporary reprieve, as the pilgrimage will gradually move into even cooler months over the next decade. But the WWA scientists are emphatic: “this will not be enough to offset the rising temperatures” .

The 2024 Tragedy as a Turning Point

Understanding the urgency of the 2026 study requires looking back at 2024. That year, the Hajj began in mid-June, and temperatures reached 51.8°C at Mecca’s Grand Mosque . More than 1,300 pilgrims lost their lives . A separate attribution analysis from ClimaMeter found that human-caused climate change made that heatwave approximately 2.5°C hotter than it would have been otherwise .

Subsequent research presented at the EGU General Assembly in May 2026 revealed that during the 2024 Hajj, heat stress conditions exceeded human survivability thresholds for several hours, even for young, healthy adults . In June 2024, the combination of heat and humidity created a window of roughly four consecutive hours during which prolonged outdoor exposure became potentially fatal without access to cooling .

What Projections Show for the Coming Decades

Even with the calendar shifting, climate models show that dangerous heat will eventually catch up. A 2019 study in Geophysical Research Letters projected that heat stress during the Hajj could again exceed the “extreme danger threshold” between 2047–2052 and again between 2079–2086 . Those windows may sound distant, but they mean that a person born today could face severe danger during a Hajj in their 20s and again in their 50s. Other research examining wet-bulb temperature thresholds has found that just half a degree of additional global warming, from 1.5°C to 2°C, substantially increases the probability of exceeding dangerous heat stress limits during the summer months in Mecca .

Saudi Arabia’s Response: Air Conditioning and Its Limits

Following the 2024 disaster, Saudi authorities strengthened anti-heat measures, with the most visible intervention being a massive expansion of air conditioning at holy sites and pilgrim facilities . These systems create cooled indoor and semi-outdoor spaces where pilgrims can recover, and they have become a central pillar of the safety strategy. The WWA study itself serves as a formal warning to authorities and international agencies about the growing risk and the need for further adaptation .

Still, the research presented at the EGU Assembly underscores the limits of technological fixes. When outdoor heat stress exceeds survivability thresholds for hours, air-conditioned shelters become essential infrastructure, but they cannot address the risks faced by pilgrims in transit between sites or those who lack ready access to indoor cooling . The study from Climate Analytics similarly warns that even in indoor spaces, if cooling fails during extreme conditions, the health risks scale catastrophically .

The picture that emerges from the WWA study and related research is not that the Hajj is about to become impossible. Instead, it is becoming more dangerous during parts of the year that were once considered safe, and the margin for error is narrowing. The calendar will provide a brief respite, but the overarching trend lines point toward a pilgrimage increasingly defined by its encounter with extreme heat.