Hong Kong reported 158.1mm of rainfall in the space of an hour on Thursday night, the highest since records began in 1884, causing widespread flooding and disrupting road and rail traffic.
The record rain, reported in the hour up to midnight on Thursday, comes just days after the city dodged major damage from a super typhoon.
Late on Thursday, authorities in the Chinese city said various districts had been flooded and emergency services were conducting rescue operations. Members of the public were instructed to stay in a safe place.
“Heavy rain will bring flash floods,” the observatory warned. “Residents living in close proximity to rivers should stay alert to weather conditions and should consider evacuation” if their homes were flooded.
No injuries were reported in the early hours of Friday.
Earlier in the week, Typhoon Haikui left a trail of destruction in Taiwan before crossing the strait and making landfall in China’s Fujian province on Tuesday.
Hong Kong’s observatory said the latest torrential rain was brought by the “trough of low pressure associated with [the] remnant of Haikui”.
The city’s Mass Transit Railway announced it would partially suspend service on one of its lines after a station in the Wong Tai Sin district was flooded, with another handful of stations also affected.
Other video clips showed cars and buses half-submerged on main roads.
The neighbouring Chinese tech hub of Shenzhen, meanwhile, was lashed by the heaviest rain since records began in 1952, state media reported on Friday.
“From 5pm Thursday to 6am Friday, the average rainfall in Shenzhen was 202.8mm and the maximum cumulative rainfall reached 469mm,” Xinhua reported, adding that the rainfall had broken multiple meteorological records since they began 71 years ago.
Heavy rain was forecast to continue on Friday, it said. Primary and secondary schools and kindergartens across the city would suspend classes for safety reasons. Services on parts of six subway lines were also suspended.
Shenzhen has prepared to discharge water from its reservoirs, according to Hong Kong officials, which they said could lead to flooding in parts of northern Hong Kong as a result.
Southern China was hit the previous weekend by two typhoons in quick succession – Saola and Haikui – though Hong Kong avoided a feared direct hit.
Tens of millions of people in the densely populated coastal areas of southern China had sheltered indoors ahead of the storms.
Climate change has increased the intensity of tropical storms, with more rain and stronger gusts leading to flash floods and coastal damage, experts say.
