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Heat and humidity are concerns for athletes competing outdoors at the Tokyo Olympics

It may end up being among the hottest Olympic Games on record

Pedestrians stand under an umbrella as they wait to cross a street on a hot summer's day in Tokyo's Omotesando area on July 16. (Charly Triballeau/AFP/Getty Images)
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Friday marked the official start of the 2020 Summer Olympics in Tokyo, a global competition and celebration delayed a year because of concerns about the coronavirus pandemic. More than 11,000 athletes will be competing, representing their home countries in a patriotic battle of athleticism and endurance.

The weather will inevitably play a role in outdoor events.

Olympic officials have already relocated several venues in response to concerns over summertime heat and humidity in the Japanese archipelago. Fortunately, aside from the steamy heat, weather might not prove too problematic.

The Olympics are finally here. Here’s a guide to help you watch the Tokyo Summer Games.

The games run from July 23 through Aug. 8. Swimming, rowing and archery events will be held toward the beginning of that period. Other events, such as soccer, handball and water polo, will span the full two weeks.

Temperatures in Tokyo during the summertime typically hover in the upper 80s, with high humidity teaming up with the heat to make conditions all the more uncomfortable.

Officials considered postponing the games until October, as was the case with the 1964 Olympics in Tokyo, but ultimately settled on maintaining the traditional schedule. Events like the marathon, some soccer matches and race walking are being held in Sapporo, Hokkaido, about 500 miles north of Tokyo. Temperatures there should be a few degrees cooler.

Before the pandemic, Olympic officials expressed particular worry for spectators, who were expected to number 500,000 to 1 million for the marathon alone. And with the heat index potentially pushing 100 degrees, it was likely that fans would face difficulties. Officials feared that, even if one in 1,000 suffered heat exhaustion or heat stroke, the resources and personnel would not be available to treat them.

This year’s Olympic festivities could be among the hottest ever, but spectators are not allowed. That might be a good thing, given the heat. Highs over the coming week will peak around 90 degrees each afternoon. A modest cool-down is possible next weekend, with highs in the lower 80s.

To the south of Japan and north of Taiwan, Category 1-equivalent Typhoon In-fa is spinning northwest toward Shanghai. It is tugging a ribbon of extreme tropical moisture into eastern China, setting the stage for large downpours and the potential for flooding. That river of moisture will clip extreme southern Japan but should miss out on affecting Shikoku, Honshu and Hokkaido.

A second weaker system, dubbed Invest 90W, could steer a plume of moisture into Japan early next week, allowing for heavy showers and downpours that could crop up each afternoon. Some places near and especially north of Tokyo could see 2 to 4 inches, primarily east of the Abukuma Mountains, by Tuesday or Wednesday.

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Depending on the evolution of that offshore system, which might grow into a tropical storm or low-end typhoon, a powerful onshore swell could arrive in about seven to 10 days’ time, coinciding with the surfing events at Tsurigasaki Beach. The prospect of a low-end offshore storm whipping up nothing but waves could be a dream come true for many surfers.

Broadly, the axis of greatest rainfall should stay offshore over the coming 10 or so days. Some places well offshore could see 40 inches or more of rainfall. It is all about location.

In sum, aside from temperature, weather does not look to be a major player in this year’s Olympic Games.

If officials had decided to postpone until October, they would probably have run a higher risk of significant typhoon impacts. For instance, in October 2019, Super Typhoon Hagibis prompted the cancellation of the Rugby World Cup in Tokyo and brought flooding across the nation, particularly the Izu Peninsula. Two weeks later, Typhoon Bualoi brought more devastating flooding.