Climate change is creating serious and growing risks for millions of pilgrims performing the Hajj, with extreme heat and humidity already pushing human physiological limits during the 2024 pilgrimage, according to a new study.
According to the findings, during several hours of the 2024 Hajj, heat stress conditions exceeded survivability thresholds even for young, healthy adults. In June 2024, the combined impact of heat and humidity created a period of approximately four consecutive hours during which prolonged outdoor exposure became potentially fatal without access to cooling or immediate relief.
The study presented at the European Geosciences Union (EGU) assembly 2026, has been prepared by a team from the Weather and Climate Services, Islamabad, Pakistan and Climate Analytics, Berlin, Germany respectively.
The paper emphasised that the weather conditions at the Hajj are going to be increasingly dangerous in the decades ahead.
Hajj is one of the five pillars of Islam. Each year, millions of pilgrims travel to Makkah to carry out rituals that require prolonged walking in the sun. The Day of Arafat has been identified as the highest risk ritual since the whole day is spent outdoors in the open with minimal shade infrastructure. While some adaptations are already visible, including indoor performance of Sa’i and the construction of more permanent shelters and structures in Mina, these changes improve safety while also altering the traditional setting of the pilgrimage, according to a statement by the EGU.
During the 2024 Hajj, approximately 1,300 fatalities were reported. Despite this, the Government of the Kingdom of Saudi Arabia plans to increase the number of pilgrims in the future, which raises serious concerns about increased exposure to extreme heat and humidity
The study authors note that future Hajj seasons will face a shifting climate pattern. Although the pilgrimage will occur during relatively cooler seasons for the next 20 to 30 years, it is expected to move back into hotter periods around 2050. At that point, the risks of extreme heat exposure are projected to intensify again, making future pilgrimages even more vulnerable to dangerous conditions.
The scientists have called for urgent adaptation and global climate mitigation. They further elaborated that mitigation is essential not only to protect pilgrims, but also to preserve the essence and traditional practice of Hajj itself. Although adaptation measures can reduce some of the danger, they cannot fully eliminate the threat if warming continues.
Climate change, the scientists said, is no longer an environmental issue but is also beginning to affect religious practices and mass gatherings worldwide.