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Why 14 inches of rain fell in Japan in just one day
The extreme rain was deadly, with at least 8 people killed and many others stranded
Record-breaking rain in Japan's Chiba Prefecture near Tokyo has killed at least eight people and sparked widespread power outages and travel disruptions, according to Japanese media reports .
In Chiba City, a total of 367 millimeters (about 14.4 inches) of rain fell in a 24-hour period ending on Thursday, the highest rainfall reading for that area since at least 1976, according to the Japanese Meteorological Agency (JMA), and more than what's ever been recorded in many US states . Incredibly, 348 millimeters fell in just 12 of those hours—about three times what the typical amount of rain fall for the entire month of August.
Thousands of travelers were stranded at Tokyo's Narita International Airport, while tens of thousands of homes have lost power across the region, according to Japanese public broadcaster NHK.
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The reason for all the rain was humid air meeting a cold air mass that has made the atmosphere "unstable," according to a JMA press conference as reported by the BBC.
These extreme rainfall events can have lasting health costs, including exacerbating chronic disease, respiratory illnesses, mental health issues and more, says Kai Chen, an environmental epidemiologist and director of the Yale Center on Climate Change and Health.
Climate change is making them worse, fueling a cycle of extreme weather. "When you have warmer temperature in the air, the air holds more moisture," Chen says. More moisture means more rain and more flooding.
"With the warming climate, we are seeing more and more these intense and frequent extreme rainfall events happening," he says.
Jackie Flynn Mogensen is a breaking news reporter at Scientific American . Before joining SciAm, she was a science reporter at Mother Jones, where she received a National Academies Eric and Wendy Schmidt Award for Excellence in Science Communications in 2024. Mogensen holds a master's degree in environmental communication and a bachelor's degree in earth sciences from Stanford University. She is based in New York City.
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