Hong Kong Endures Record-Breaking August Rainfall, Raising Climate Concerns

On August 5, 2025, Hong Kong experienced its heaviest August rainfall since records began in 1884, with over 350 millimeters (13.8 inches) recorded by mid-afternoon. The Hong Kong Observatory issued a "black" rainstorm warning—the highest level in its three-tier system—for the fourth time in eight days, marking an unprecedented frequency of such alerts within a single year.

The torrential downpour led to widespread disruptions across the city. Schools, courts, and outpatient clinics were closed, and major hospitals faced ankle-deep flooding at entrances, causing temporary service suspensions. Transportation networks, including airports and bridges, experienced delays and reduced operations due to poor visibility.

This extreme weather event is part of a broader pattern of severe rainfall and flooding affecting the Pearl River Delta region, including Guangdong province and Macau, which meteorologists link to climate change.

Immediate Impacts on Hong Kong

The unprecedented rainfall and subsequent flooding have had profound social and societal impacts on Hong Kong:

• Public Safety and Health: The flooding led to hazardous conditions, with streets turning into rivers and public infrastructure being compromised. Major hospitals, including Queen Mary Hospital, reported ankle-deep water at entrances, necessitating temporary service suspensions. The risk of waterborne diseases may increase due to stagnant water and overwhelmed sanitation systems.

• Education and Judiciary Disruptions: The closure of schools and courts disrupted daily life and essential services. The judiciary announced that courts, tribunals, and register offices would remain shut until at least two hours after the 'black' rainstorm alert was canceled.

• Transportation and Economic Impact: The flooding caused significant transportation disruptions, including delays and cancellations of flights, ferry services, and road transport. Airports across the region reported cancellation rates of around 20%. The economic ramifications are substantial, affecting businesses, supply chains, and daily commerce.

Regional Context and Broader Implications

The extreme weather in Hong Kong is part of a broader pattern affecting the Pearl River Delta region, including Guangdong province and Macau. Guangdong province experienced deadly flash floods days earlier that killed five people and triggered large-scale rescue operations. Several rivers in the region approached dangerous levels, with some hydrology stations recording their highest water levels since 2017–2018. Meteorologists link these occurrences to climate change, highlighting the urgent need for enhanced urban resilience and emergency preparedness in the face of escalating climate-related challenges.

Government Response and Emergency Measures

In response to the severe weather, the Hong Kong Government activated emergency response mechanisms, including the Emergency Monitoring & Support Centre and the Drainage Services Department's Emergency Control Centre, to manage the crisis. The Hong Kong Observatory advised the public to take shelter in a safe place, stating, "Persistent rainstorm will cause serious road flooding and traffic congestion. Members of the public are advised to take shelter in a safe place."

Historical Context

This event marked the heaviest August rainfall in Hong Kong since records began in 1884. The issuance of four "black" rainstorm warnings within eight days set a new record for the frequency of such alerts within a single year. Hong Kong's climate is characterized by a monsoon-influenced subtropical climate, with a rainy season typically spanning from May to September. The city receives an annual average of 2,200 millimeters of rainfall, more than half of which usually falls from June through August.

Conclusion

The record-breaking rainfall and its associated disruptions underscore the pressing need for Hong Kong to enhance its urban resilience and emergency preparedness. As climate change continues to contribute to more frequent and severe weather events, proactive measures are essential to safeguard public safety, maintain essential services, and mitigate economic impacts.