breaking news: August rainfall record in Hong Kong shattered in a single day
Heavy Rain and Landslides Hit Hong Kong: A Record-Breaking Black Rainstorm Event
Hong Kong experienced a historic black rainstorm event on Tuesday, 5th August, with the alert remaining in place for an unprecedented 16 hours and 35 minutes, breaking the record for the longest duration of a rainstorm alert in the city.
The heavy rain and winds caused flooding on some roads and at least 13 landslides citywide. One of the most notable incidents occurred on Po Shan Road, a site of a deadly landslide in 1972 that killed 67 people.
The torrential downpour on Tuesday was a sharp departure from an unusually dry first half of the year, according to the weather agency. The photo of a blocked hospital entrance, taken by Reuters, showed the extent of the flooding.
Since 1884, Hong Kong has maintained meteorological records that include rainfall and rainstorm warnings. The black rainstorm warning, the highest level of alert indicating very heavy rainfall (hourly rainfall exceeding 70 mm), has been officially used since the establishment of the modern Hong Kong Observatory system in 1992.
In 2025 alone, Hong Kong issued 51 rainstorm warnings, including four black rainstorm signals in just eight days—surpassing previous records in the number of warnings per year and reflecting increasingly extreme weather patterns. On August 6, 2025, Hong Kong experienced an 11-hour black rainstorm warning, the second-longest on record, with an extraordinary 358.8 mm of rain falling in a single day at the Tsim Sha Tsui Observatory. This was the highest daily rainfall for August since records began in 1884.
These extreme rainfall events lead to significant flooding of streets and landslide warnings, temporarily paralyzing parts of the city. Infrastructure disruptions included temporary closures of MTR (mass transit railway) exits at several stations such as Kwun Tong, Sham Shui Po, Wong Tai Sin, and Wan Chai during the 2025 events. Flights suffered delays, cancellations, and diversions, with reports of over 100 flight disruptions during severe black rainstorm episodes due to poor visibility and runway flooding.
The economic impact of these disruptions is significant. Disruptions to transport and infrastructure from black rainstorms can have wide-ranging economic consequences, including flight delays and cancellations affecting business travel and cargo, temporary shutdowns and delays in public transit affecting commutes and economic productivity, and flood damage to properties, roads, and utilities requiring costly repairs and emergency response.
While precise economic loss data linked specifically to black rainstorm warnings since 1884 are not detailed in the search results, the repeated and increasing frequency of these events suggests a growing economic burden, intensified by the challenges extreme weather poses to Hong Kong’s dense urban environment.
Experts attribute the growing frequency and severity of black rainstorm warnings in recent years partly to climate change, which exacerbates weather instability, causing extreme dry and wet conditions. Hong Kong’s black rainstorm warning system (operational since 1992) remains a critical tool for urban weather management and disaster preparedness amid these changing climatic conditions.
The storm resulted in insurance claims of around HK$1.5 billion (US$191 million). Stuart Millis, an engineering geologist and associate director at the consultancy Arup, states that the recent back-to-back rainstorms can saturate soils and raise groundwater levels beyond normal levels. As of 2.35pm, at least 361 passenger and cargo flights were delayed, with 11 services cancelled at the Hong Kong International Airport.
Parts of mainland China have been experiencing extreme weather over the past week, including Shanghai and deadly flooding in Beijing. The black rain warning was issued in the early morning and remains in effect until 5pm. Some metro exits were shut earlier in the morning. By 2.15pm, parts of Hong Kong had received up to 400mm of rain. All court hearings have been adjourned due to the weather conditions.
The sudden and heavy rainfall during the black rainstorm event is a key focus of weather-forecasting agencies, as such events can lead to flooding and landslides, as observed in Hong Kong on August 5, 20XX. Infrastructure disruptions, such as airport flight delays and cancellations, temporary public transit closures, and property damage from flooding, have significant economic implications, underscoring the importance of accurate weather-forecasting in managing extreme weather events.
