The national broadcaster NHK said the weather agency issued a rare “special warning” about the powerful storm.

The move came as the Japan Meteorological Agency issued its highest alert for the Kagoshima region, a warning that comes when it forecasts conditions only seen once in several decades.

Typhoon Nanmadol has been classified as a super typhoon by the US Navy's Joint Typhoon Warning Center.

It made landfall in southwestern Japan on Sunday night. It was packing gusts of up to almost 250km/h and had already dumped up to 500mm of rain in less than 24 hours.  

The violent typhoon has forced flight cancellations, triggered power blackouts and brought Japan's famous bullet train to a standstill.

The typhoon has been slowly heading north to the country's main southern island of Kyushu.

“There are risks of unprecedented storms, high waves, storm surges, and record rainfall,” Ryuta Kurora, the head of the Japan Meteorological Agency’s forecast unit, told reporters.

“Maximum caution is required,” he said, urging residents to evacuate early.

“It’s a very dangerous typhoon.” 

“The wind will be so fierce that some houses might collapse,” Kurora told reporters, also warning of flooding and landslides.

The evacuation warnings call on people to move to shelters or alternative accommodation that can withstand extreme weather.

But they are not mandatory, and during past extreme weather events authorities have struggled to convince residents to take shelter quickly enough.

Kurora said even inside strong buildings, residents should take precautions.

“Please move into sturdy buildings before violent winds start to blow and stay away from windows even inside sturdy buildings,” he told a t press conference.

Japan is currently in typhoon season and faces around 20 such storms a year, routinely seeing heavy rains that cause landslides or flash floods.

In 2019, Typhoon Hagibis smashed into Japan as it hosted the Rugby World Cup, claiming the lives of more than 100 people.

A year earlier, Typhoon Jebi shut down Kansai Airport in Osaka, killing 14 people.

And in 2018, floods and landslides killed more than 200 people in western Japan during the country’s annual rainy season.

Scientists say climate change is increasing the severity of storms and causing extreme weather such as heat waves, droughts and flash floods to become more frequent and intense.

The Citizen