'Oppressive' heat, humidity could spell disaster for 2020 Tokyo Olympics

By Katy Galimberti, AccuWeather staff writer
February 27, 2018, 9:00:24 AM EST

While the Winter Olympics just came to a close in PyeongChang, the world will again turn its focus to Asia when Tokyo hosts the 2020 Summer Olympics.

Organizers are busy preparing for the games, but some experts are questioning if alterations will be needed to keep athletes safe.

Tokyo in late July to mid-August is hot and humid, which puts certain athletes, especially distance runners, at risk for heatstroke.

Heatstroke occurs when the body temperature rises to 40 degrees Celsius (104 degrees Fahrenheit) or higher.

Makoto Yokohari, an adviser for the Tokyo Olympics committee and professor at Tokyo University, conducted recent research that concluded athletes and even spectators could be in danger if precautions aren't taken.

tokyo 2020 olympics

Images of projection mapping are illuminated on the Tokyo Metropolitan Government building during the Tokyo 2020 flag tour festival for the 2020 Games in Tokyo, Monday, July 24, 2017. (AP Photo/Shizuo Kambayashi)

While Tokyo has hosted the Olympics before, they took place in October when conditions were cooler.

Average highs in the heat of the summer hover near 30 C (in the mid-80s F) but can rise to 33-35 C (into the 90s) at times, according to the Japan Meteorological Association.

“These will be some of the worst conditions in the history of marathon running,” Yokohari told The Times.

Relative humidity at that point in the summer is near 80 percent and combined with an extremely high dew point, results in "oppressive" conditions, AccuWeather Meteorologist Adam Douty said.

Yokohari and his team went through the exact men's marathon course at the same time of year at the same starting point in the summer of 2016. The course offers little to no shade, which makes it even more dangerous for the runners.

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The team found that after only 30 minutes of the course, runners would be at "extreme danger."

Even those simply watching the race were "vulnerable" or in "danger."

Yokohari's team has told Olympic officials to make changes including changing the course and altering the start time to be earlier in the day.

Other athletes could be in jeopardy as well.

While the extreme humidity and high heat poses a major threat, the summer is Japan's wettest time of the year.

"Tropical moisture commonly moves across Japan during the summer, resulting in heavy downpours," Douty said. "Tropical activity in the West Pacific really ramps up in July and August, so it is not out of the question for a tropical system to impact the games."

The games last just over two weeks - a time period in which Tokyo averages about 89 mm (3.5 inches) of rain.

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