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Localised Heavy Rain Advisory

The development and movement of heavy rain that affects Hong Kong can be vastly different. Sometimes the heavy rain may be widespread, while on other occasions it may be localised and cause serious flooding only in certain districts but not others.

The issuance of the Localised Heavy Rain Advisory is based on the recorded and forecast regional rainfall amount, for example, when heavy rain with more than 70 millimetres of rainfall has fallen or is expected to fall in an hour in individual districts of Hong Kong, which may bring serious flooding and risks to the districts. If heavy rain at that time does not extend generally over Hong Kong and reach the criteria for a Red or Black Rainstorm Warning Signal, the Observatory will issue the Localised Heavy Rain Advisory, indicating the affected districts and the respective recorded or expected rainfall, to alert the public of potential flooding due to heavy rain in the districts, so as to take precautionary measures. The advisory also reminds relevant government departments to take appropriate responsive actions, such as emergency measures to alleviate the impact of flooding in concerned districts.

In general, the Localised Heavy Rain Advisory is applicable to all areas in Hong Kong. However, when heavy rain has affected the northern part of the New Territories, after the Observatory issued the Special Announcement on Flooding in the northern New Territories, the Localised Heavy Rain Advisory will only be applicable to other areas in Hong Kong afterwards. When localised heavy rain persists, or there is or will be changes in the affected districts, the Observatory will update the advisory appropriately. Furthermore, if heavy rain is forecast to extend to affect widespread areas and reach the criteria of Red or Black Rainstorm Warning Signal, the Observatory will issue the corresponding warning signal.

POINTS TO NOTE

  1. Members of the public in the districts affected by heavy rain should take appropriate measures to prevent possible loss caused by flooding. People should also be cautious when travelling to the concerned districts.
  2. The public can get the latest situation of heavy rain via radio, television, the Observatory website and mobile app "MyObservatory". They can also get hold of the latest conditions by making reference to the regional rainfall information and the radar imageries, which illustrate the distribution and movement of rain areas, on the Observatory website and "MyObservatory".