Record rainfall in Japan’s Chiba prefecture, near Tokyo, has killed at least four people and injured five, causing widespread flooding, landslides and transport disruption. The event matters because authorities described it as unprecedented by Japan’s historical weather standards, with emergency warnings issued and large-scale evacuations ordered.

More than 20,000 households lost power, around 7,000 travellers were stranded overnight at Narita Airport, and over 100,000 households were asked to evacuate. Chiba recorded over 100mm of rain an hour from Thursday afternoon, while rail services and highways remained disrupted; the rainfall is expected to continue into late Friday amid an unusually active regional typhoon season.