On 20.05.2026, parts of Hong Kong‘s northern New Territories experienced intense rainfall that prompted a series of official warnings and multiple reports of flooding. The Hong Kong Observatory issued an amber rainstorm warning at 9:00 p.m., signalling that rainfall rates had surpassed 30 millimetres per hour in some locations and were likely to persist. As conditions intensified, a separate flooding alert was posted for the northern New Territories at 9:45 p.m., with low-lying and poorly drained districts identified as particularly vulnerable.
The Observatory’s hourly bulletin (Press Weather No. 192) at 21:08 HKT recorded an air temperature of 29 degrees Celsius and a relative humidity of 83 percent at 9:00 p.m. Officials also issued a localised heavy rain advisory noting that more than 70 millimetres of hourly rainfall had fallen or was expected in the North District, raising the risk of serious flooding. In addition, a thunderstorm warning was in force and set to remain effective until 10:00 p.m., with the bulletin warning of a few squally thunderstorms across Hong Kong.
Where the storm struck hardest
Field reports and the Observatory both pointed to the northern fringe of the territory as the epicentre of the disruption. Ta Kwu Ling emerged as one of the most affected areas, with residents and emergency services noting widespread water accumulation in streets and low-lying plots. The advisory emphasised that places with poor drainage should take immediate precautions to avoid damage. Between 7:45 and 8:45 p.m., lightning was detected in New Territories East, compounding the safety risks for anyone outdoors.
Observatory readings and rainfall distribution
The hourly data released in Press Weather No. 192 provides a snapshot of the event: the Observatory reported a concentrated burst of precipitation across the northern districts and variable amounts elsewhere. Recorded hourly rainfall ranges included North District from 2 to 49 millimetres, Yuen Long from 0 to 37 millimetres, Tai Po from 0 to 16 millimetres, Tsuen Wan from 0 to 8 millimetres, and both Sai Kung and Sha Tin showing 0 to 1 millimetre in that interval. These figures underscore the localized nature of the downpour.
Temperature snapshot across stations
The bulletin also listed air temperatures at a number of observation points at 9:00 p.m., reflecting warm, humid conditions that often accompany summer convective storms. Notable readings included Chek Lap Kok at 30 degrees Celsius, Tsing Yi and Happy Valley at 29 degrees, while Ta Kwu Ling was recorded cooler at 25 degrees. Other locations such as Tai Po, Sha Tin, Tuen Mun, and Tsuen Wan registered in the high twenties, illustrating a broadly warm evening atmosphere.
Advice for residents and implications
Authorities urged people in affected districts to take straightforward precautions: avoid walking or driving through flooded streets, secure property in low-lying areas, and stay tuned to official channels for updates. The use of amber and thunderstorm warning signals aims to convey both urgency and actionable guidance — the amber rainstorm warning denotes heavy rainfall likely to persist and the thunderstorm warning highlights potential lightning and squally conditions. Residents in the northern New Territories were specifically reminded that hourly rainfall exceeding 70 millimetres can cause rapid water rise and pose serious hazards.
What the data suggests for short-term risk
In practical terms, the combination of high humidity, warm temperatures and localized intense downpours that occurred on 20.05.2026 favours sudden surface runoff and overwhelmed drainage systems in vulnerable spots. Emergency services and municipal crews typically focus on clearing drains, attending to stranded vehicles and responding to flooding reports during such episodes. For urban planners and community groups, these events are a reminder of the importance of resilient drainage and timely public messaging when heavy rain events strike.
Where to get updates
For ongoing information, residents were directed to consult the Hong Kong Observatory bulletins and official government channels, which provide real-time readings, warning statuses and safety advice. The Observatory’s detailed postings, like Press Weather No. 192 issued at 21:08 HKT on 20.05.2026, remain the authoritative source for rainfall amounts, temperature measurements and lightning detection during active weather episodes.
