Hong Kong’s heaviest rainstorm since records began in 1884 flooded the financial hub’s streets and sent torrents of water rushing through subway stations, bringing much of the city to a standstill and forcing the stock market to scrap trading on Friday.

The downpour, which caught many residents off guard and came just a week after a super typhoon shut the city, caused the observatory to raise its highest rainstorm alert. Schools were suspended and workers stayed home as bus operators halted services. Extreme weather conditions were expected to last until 6 pm, the government warned.

The short notice of official warnings meant businesses and residents had little time to prepare for the deluge, which tore up roads, flooded shopping malls and submerged vehicles. At least 85 people were injured, including two in serious condition, the government said. Insurance claims may exceed $100 million and could be comparable to Typhoon Mangkhut’s $470 million in 2018, according to Bloomberg Intelligence.

The topography of Hong Kong — roads and buildings built into steep hillsides — makes the city vulnerable to flooding and landslides from torrential summer rains that have steadily intensified over time. This particular downpour was caused by the remnants of Typhoon Haikui. Yet the scenes recorded show damage on a scale the city hasn’t seen in recent decades.

The observatory raised the highest “black” rainstorm warning at 11:05 p.m. local time Thursday. The warning means more than 70 mm of rain has fallen in an hour and is likely to continue, while residents should avoid travel. The warning was still up at noon.

A record 158.1 mm (6 inches) of rain was recorded at the observatory headquarters in Tsim Sha Tsui between 11 pm Thursday and midnight. More than 600 mm of rain was recorded over much of Hong Kong island in the past 24 hours, according to the observatory.

All trading was suspended on the city’s stock market for the duration of Friday, the local exchange operator said in a statement at midday.

At Wong Tai Sin subway station in Kowloon, videos circulating widely on social media showed waterfalls of rain pouring into concourses as trains continued running. The lower floor of a nearby shopping mall filled with water as furniture floated on the surface. MTR Corp. said it suspended part of its Kwun Tong Line due to flooding at the station.

Hong Kong’s Wong Tai Sin subway flooded due to heavy rain！ pic.twitter.com/jEiM55eKRK
— Jim yang (@yangyubin1998) September 7, 2023

The city’s leader John Lee told government departments to respond with all-out efforts to deal with the “severe” flooding in most parts of the finance hub. The lack of forewarning contrasted with the approach of Super Typhoon Saola, when the city’s chief secretary held a press conference flanked by department heads to address potential risks.

In the village of Stanley on the south side of Hong Kong island, rivers of water ripped open pavements to expose underground cables. A damaged minibus was abandoned in the middle of a waterfront road, surrounded by debris. Floods had carved channels in the nearby beach, carrying sand into the sea. Nearby, part of a hillside had fallen on to the road to Tai Tam.

There were seven landslides recorded as of 8 a.m., six of which were on Hong Kong island.

Rain is expected to ease off gradually this afternoon, an observatory spokesperson said, adding there is no timetable for the black rainstorm warning to be lifted.

Before the rains hit, the city was still cleaning up from Saola, which forced Hong Kong to shut down on Friday and Saturday last week. That storm, the strongest to hit Hong Kong since Mangkhut in 2018, toppled trees and blocked roads. It was only the sixth time in the past four decades that the observatory raised its highest storm warning.

The storms are the latest examples of extreme weather experienced around the world this summer. In late July and August, dozens of people died in northern areas of China including Beijing due to flooding from a typhoon.

–With assistance from Dominic Lau, Danny Lee, Olivia Tam, Filipe Pacheco and Janet Paskin.

Photograph: Vehicles stranded in floodwaters during heavy rain in Hong Kong. Photo credit: Justin Chin/Bloomberg

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