Hong Kong Issues Black Rain Warning for Fourth Time in a Week as Storms Disrupt City Life

Hong Kong experienced violent storms that triggered the highest rain warning on August 5 for a record-breaking fourth time in one week. The city recorded flight delays, commuter chaos and service closures, reported Bloomberg.

Certain regions of Hong Kong including the central business district received as much as 400 millimeters (15.7 inches) of rain from midnight through noon, according to the Hong Kong Observatory, as reported by Bloomberg. The black rain warning was issued during the early morning and will remain in effect until at least 3 pm local time.

What is Black Rain Signal?

The black rain signal is the highest in Hong Kong’s three-tier warning system. It is issued when heavy rain exceeding 70 millimeters in an hour has fallen or is expected to fall imminently. The second-highest warning is red, followed by amber. The latest black rain warning was issued just before 6 am, following a similar one on August 4 that lasted a few hours.

Stuart Millis, an engineering geologist and associate director at consultancy Arup told Bloomberg that the back-to-back rainstorms of recent weeks can saturate soils and raise groundwater levels beyond normal levels.

“You are having one black rainstorm, then two, three days later you are having another red rainstorm, followed a couple of days later by another black rainstorm,” he said in an interview. “It’s that cumulative impact that causes concern from a geotechnical perspective.”

Flights Delayed, Roads Flooded

The Hong Kong International Airport was among the worst affected, with over 100 flights delayed, one departure cancelled and two arrivals diverted to other airports, according to the operator.

The airport issued an advisory for passengers on its official website at 10 am on August 5, warning passengers to check with their airlines and allow extra time due to possible disruptions in public transport.

“Due to inclement weather conditions, flight operations at Hong Kong International Airport may be affected. Please contact your airline for the latest flight information or check with the airport's website before departing for the airport. The public transport services to and from the airport may also be affected. Passengers are advised to allow sufficient travel time to and from the airport,” stated Hong Kong International Airport on its official website.

Citing government data, Bloomberg reported that the downpour flooded some roads and at least 12 landslides have been reported citywide. That includes Po Shan Road in the high-end Mid-Levels neighbourhood on Hong Kong Island, the site of a deadly landslide in June 1972 that killed 67 people.

The rainfall also caused some metro exits to shut earlier in the morning, along with adjournment of all court hearings. The open outcry market for the Hong Kong Gold Exchange will also be closed for the day.

Neighbouring Shenzhen also issued a city-wide red alert at 4 am on the morning of August 5, the first of its kind since 2018, according to a local media report.