HONG KONG – The worst torrential rain in about 140 years could cost Hong Kong more than US$100 million (S$136 million), according to a Bloomberg Intelligence estimate.

The heavy rain started on Thursday, and in the hour leading up to midnight, the city’s weather observatory recorded hourly rainfall of 158.1mm at its headquarters, the highest since records began in 1884.

The Hong Kong Observatory said it recorded more than 600mm of rainfall at its headquarters over 24 hours – roughly a quarter of the city’s annual average.

The downpour that pummelled the city on Thursday night and into Friday morning wrecked vehicles, flooded subway stations and damaged shopping malls.

Rail operator MTR Corp has already suspended part of its Kwun Tong Line due to flooding near Wong Tai Sin station.

The typhoon that hit the city last week, Saola, did less damage, according to the BI report, because even though it was the most severe since Typhoon Mangkut in 2018, it did not trigger much flooding. 

Mangkut, which did cause floods, resulted in US$470 million in damage. Typhoon Hato the year before triggered US$140 million in claims.

Schools were suspended on Friday, while employers were called on to prioritise staff safety and adopt flexible work arrangements, the government said in a statement. The stock market cancelled trading due to the rainstorm.

Extreme conditions under heavy rain will continue on Friday night and remain at least until midnight, according to Hong Kong Chief Secretary Eric Chan. BLOOMBERG, AFP