Schools closed as city issues second ‘black’ rain warning – its highest – in a month amid torrential rain, strong winds.

More than 150mm of rain was recorded over most parts of Hong Kong from midnight into Monday morning, with rainfall exceeding 300mm in some areas, data showed.

The Hong Kong Observatory issued a “black” rainstorm warning – its highest – for about six hours before it was downgraded at 10.30am (02:30 GMT), a month after the city was paralysed by the worst floods in 140 years.

While Koinu, which killed one person in Taiwan last week, had weakened into a severe tropical storm, it still brought significant disruption.

Schools and childcare centres were ordered to shut and the morning session at the Hong Kong Stock Exchange was suspended. Trade was expected to resume at 2pm (06:00 GMT).

Hundreds of passengers were stranded at Hong Kong’s airport overnight and underground metro stations as Koinu disrupted flights and transport, public broadcaster RTHK reported.

In early September, Hong Kong was brought to a standstill by torrential rain that swamped streets and flooded shopping malls and metro stations. A “black” warning was also issued then.

In China’s Guangdong province – where Koinu is expected to sweep past en route to Hainan island – the cities of Zhuhai and Jiangmen issued a Level III emergency response, according to the Xinhua news agency on Sunday.

The alert meant more than 35,500 fishing boats had to return to port, while dozens of coastal scenic areas were temporarily closed.

Southern China is frequently hit during the summer and autumn seasons by typhoons that form in the warm oceans east of the Philippines and then travel west.

But climate change has made tropical storms more unpredictable while increasing their intensity – bringing more rain and stronger gusts that lead to flash floods and coastal damage, experts say.