‘The Largest Hajj in History’ Is Taking Place In Extreme Heat

On Monday, millions of people assembled in Mecca, Saudi Arabia, for what could be a record-breaking Hajj pilgrimage. It could also be among the hottest ever.

As one of the five pillars of Islam, the Hajj is expected to be performed by every able-bodied Muslim with the financial means to do so at least once in their lives. The annual five- to six-day pilgrimage to Mecca was already one of the world’s largest religious gatherings, but this year, the first since pandemic-era restrictions were lifted, more than 2.5 million people have reportedly descended on the holy site, undeterred by “extreme” daily temperatures over 110 degrees. Saudi officials say it will be “the largest Hajj pilgrimage in history.”

Because the dates of the annual Hajj are dictated by the lunar calendar, the pilgrimage season has fallen during Saudi Arabia’s hottest months since 2017 and won’t move out of them until 2026. But while there were, of course, many summer Hajj seasons before this one, the Middle East has been warming twice as fast as the rest of the globe, meaning it’s much hotter now than when the Prophet Mohammed performed the first Hajj some 1,400 years ago. Looking at just the past 30 years in Mecca, there has been a “significant” nearly 2-degree Celsius (3.6°F) rise in the average wet-bulb temperature — that is, the preferred metric for measuring heat-related stress on the human body — Yale Climate Connections reports, adding “this increase is well above the global average, and can be largely attributed to human-caused global warming.”

Since the Hajj moves 11 days earlier every year, the pilgrimage is finally transitioning out of the worst months of summer beginning this year (the hottest recent Hajj hit 122 degrees in August 2018). But June 2023 hasn’t cooled down much; a hot spell in the Kingdom has local authorities mobilizing in anticipation of heat-related illnesses. Though the 113-degree daily highs aren’t unheard of in Saudi Arabia this time of year, they don’t tell the full story of the heat the pilgrims face, either. The so-called “penguin effect,” in which a crowd retains heat, will exacerbate those already eye-popping temperatures. There are reportedly 32,000 health workers and “thousands” of ambulances standing by to address dehydration, heatstroke, and exhaustion, and 217 beds are said to be set aside on-site for sunstroke patients.

Regional religious leaders around the globe are also warning pilgrims from their countries to protect themselves from Mecca’s heat since the lack of acclimation makes foreigners uniquely susceptible to extreme temperatures; some “71% of deaths among pilgrims could be attributed to elevated temperatures,” one study found.

But all the advice and medical preparations still might not be enough. Many Muslims who perform the Hajj are elderly — having saved over the course of a lifetime to make the pilgrimage — and thus at high risk in the heat. On top of that, the pilgrimage is physically demanding: The estimated total walking distance, including the circling of the Kaaba and “miscellaneous walking to get to the pick-up points of the tour,” is about 36 miles over five days, according to a study on Hajj-related blisters. Much of that journey is now made in massive air-conditioned tunnels that connect significant sites, though key rites are performed outdoors and under the sun — some 20 to 30 hours of exposed outdoor activity in total. The result is “roughly one in every 1,000 religious visitors to Mecca dies, many from cardiorespiratory attacks,” The Economist reports.

There is a bit of good news for pilgrims this year, though. While it is hotter than in recent years, a major difference is that there isn’t much humidity forecast for Mecca this week — and it is typically humidity, which hinders the body’s natural cooling abilities, that makes the Hajj pilgrimage deadly. (Though not always: In addition to heat exhaustion, a 1990 stampede that resulted in the deaths of 1,400 people is believed to have started due to panic over rising temperatures in a tunnel where a ventilation system broke down). Still, it will be critical for pilgrims to keep hydrated, watch their electrolytes, and maximize time in air-conditioned tents supplied by the Saudi authorities — though those same tents can quickly become deadly if AC fails, since they also trap dangerous humidity inside.

In theory, the Hajj should become safer in the immediate future as it moves deeper into Mecca’s cooler months. But those who are able might want to prioritize making their obligatory pilgrimage sooner rather than later. Come 2047, when Hajj season is in the summer again, the planet will be even warmer than it is now — and perhaps even too dangerous to participate outdoors.