Japan is heading for a warmer-than-average summer, according to weather forecasters, in a development that could mean periods of extreme heat at the Tokyo Olympics.
Forecasts by the Japan Meteorological Agency and Weathernews, the private meteorological company, suggest the North Pacific High pressure zone will extend towards Tokyo in July.
If the early predictions are correct, heat and humidity will be an added concern for athletes, especially if Covid-19 means they do not have a long acclimatisation period in the country before the Games.
High temperatures could also make it harder to implement Covid-19 countermeasures, such as the wearing of masks.
The Olympics are due to be held between July 23 and August 8, at the peak of Japan’s notoriously hot and humid summer. The Paralympics are scheduled from August 24 to September 5. Both events were postponed by a year because of the coronavirus pandemic.
A hot summer would be especially unfortunate because last July, when the Games were originally due to be held, was unusually cool in Japan.
Weathernews said it expected temperatures to be higher than average in the Tokyo area, and closer to normal in the northern and western parts of Japan. It forecast peaks of temperature in late July and late August.
“The key to the heat is the high pressure zones in Tibet and the North Pacific,” said Tatsuya Sasaki, a forecaster at Weathernews. “If the North Pacific and Tibetan highs overlap then we can expect a heatwave.”
Daily maximum temperatures average about 30 degrees in the Tokyo summer and relative humidity averages around 80 per cent. But if there is such a “double high” in atmospheric pressure, Japan could experience consecutive days with peak temperatures above 35C, said Sasaki.
“We’re expecting temperatures above average between June and August,” said Motoaki Takekawa at the JMA. He said the forecast was still highly uncertain and the weather was likely to be closer to average in the second half of the summer.
Longstanding concerns about the summer heat in Tokyo meant the Olympic marathon was moved to the northern city of Sapporo. When Tokyo hosted the Olympics in 1964, they were held in October.
The Tokyo 2020 organising committee discussed the forecast at an executive board meeting last week, warning that it needed to harmonise measures to tackle Covid-19 and the extreme heat.
It is considering how to maintain social distancing under sun shade tents, how to avoid heatstroke for people wearing masks and how to triage the flow of heatstroke victims.
In its original bid document for the Games, Tokyo said of its summer: “With many days of mild and sunny weather, this period provides an ideal climate for athletes to perform at their best.”