Even if no record is set, high humidity, which makes temperatures feel hotter and hinders the body’s ability to cool down, means these Games have likely been historically tough on athletes.

“When you take into account not only the temperature, but also humidity, I would say that a Tokyo Summer is the worst in the history of Olympics,” Makoto Yokohari, professor of environment and urban planning at the University of Tokyo, told CNN.

Any heat record set this week may not last long. Climate change means temperatures are increasing at such a rate that by 2085 there will only be 33 cities remaining with temperatures suitable to host the summer Olympics, according to a 2016 study published in the Lancet that looked at Northern hemisphere locations.

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