Hong Kong issued its highest black rain warning for the fourth time in a week on 5 August 2025, causing widespread flooding, flight delays, and service disruptions across the city.

The Hong Kong Observatory (HKO) issued the black rain warning at 5:50 am on 5 August 2025, marking the fourth such alert in eight days, a record since the rainstorm warning system began in 1992. Over 350 mm of rain fell by 2 pm, the highest daily rainfall for August since 1884. The deluge flooded streets, hospitals, and car parks, particularly in areas like Pok Fu Lam, Mid-Levels, and Sai Kung. The warning, indicating rainfall exceeding 70 mm per hour, lasted 11 hours and 15 minutes, the second-longest on record.

The storms disrupted public services, with over 100 flights delayed, two cancelled, and metro exits closed at stations like Sham Shui Po and Tai Po. Schools, courts, and hospitals scaled back operations, with Queen Mary Hospital’s emergency ward inundated. Landslide warnings were issued due to saturated soils, with 12 landslides reported, including at Po Shan Road, a site of a deadly 1972 landslide. Neighbouring Shenzhen issued a red alert, reflecting regional weather chaos driven by an active southwest monsoon.

Experts link the extreme rainfall to climate change, which increases atmospheric moisture and intensifies storms. The cumulative effect of back-to-back rainstorms has raised groundwater levels, heightening landslide risks in Hong Kong’s hilly terrain. The HKO warned of continued heavy showers, urging residents to avoid steep slopes and flooded areas. Temporary shelters were opened for those affected.

Public transport faced significant disruptions, with bus routes suspended and the Peak tram halted. The Hong Kong Stock Exchange remained open, following a policy change to continue trading during weather events. Authorities advised residents to stay indoors and cancel non-essential travel, with the airport recommending extra travel time.

The storms follow deadly floods in Guangdong, where five died, highlighting the broader impact of climate-driven weather across the Pearl River Delta. Hong Kong’s annual rainfall averages 2,200 mm, with over half typically falling between June and August, but this year’s intensity is unprecedented. Enhanced coordination among government agencies is needed to improve flood and landslide preparedness.

In conclusion, Hong Kong’s record-breaking black rain warnings reflect the growing threat of climate-driven extreme weather. Strengthening infrastructure and early warning systems is crucial to mitigate future disruptions and ensure public safety.

Source: Outlook Business