San Francisco Frontiers - Tokyo suffers longest streak of rainy days on record

Climate change fuelled by fossil fuel emissions increases moisture in the atmosphere, making heavy rain more likely.

The weather globally is also being shaped this year by the El Nino phenomenon, which shifts winds, air pressure and cloud patterns and can bring heavy rain to some areas and droughts elsewhere.

The Japanese capital's rainy season is normally in June, but it has suffered regular heavy downpours throughout the summer months, as well as heavy flooding in the wider Tokyo region.

The stretch of rainy days was the longest since records began in 1886.

Masayuki Kyoda, an official at the Japan Meteorological Agency (JMA), told AFP that "the distinctive weather map during this month is in part because of El Nino", bringing higher temperatures in the Pacific Ocean.

"Autumn rain fronts are staying longer than usual," Kyoda said, referring to Tokyo's rainy season, because a high pressure system in the Pacific is also remaining longer than normal.

He said that although it was not possible to directly link the streak to climate change, a JMA report last year concluded that "global warming was impacting Japan's weather long-term, including through more precipitation".

The previous record of the longest streak of rainy days in Tokyo was 33 between June 27 and September 29, 2019, said Kazuhiro Hirono, another JMA official.

The Mainichi Shimbun daily reported that central Tokyo had been soaked by 629 millimetres (24.8 inches) of rain in September through to Monday, nearly three times the normal level.

That was approaching the September record of 670.9 millimetres set in 1958.

Tokyo's wet weather comes as 1.7 million people were affected by recent flooding in Thailand after an intense weather system hit the region, with 23 people killed since mid-September.

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