The Hong Kong tropical cyclone warning signals, or informally typhoon signals, are a set of signals used to indicate the threat or effects of a tropical cyclone. The warning will be renewed if thunderstorms are expected to persist beyond the time stated in the original warning or cancelled if thunderstorms are not expected to occur in the remaining part of the original validity period. Thunderstorm warnings issued by the Hong Kong Observatory are intended to give short-term (within one to a few hours) notice of the likelihood of thunderstorms affecting any part of Hong Kong. Both heavy rain and thunderstorm warnings were issued to the public through press release, radio broadcast and telephone calling service to subs… When the Thunderstorm Warning is in force, the lightning location information enables the public to identify areas affected by the thunderstorms. Widespread heavy rain is affecting Hong Kong. Once issued, the warning is broadcast over radio and television, and announced on the Observatory's website, the “MyObservatory” mobile app and the Dial-a-Weather system … The announcement is updated at appropriate intervals until the likelihood of landslips diminishes. The Red signal means that heavy rain could cause serious road flooding and traffic congestion, and may affect schools and public examinations. 12th August 2020 – (Hong Kong) Thunderstorm warning was issued by Hong Kong Observatory at 8.40pm yesterday and it is still in force. Intense gusts reaching 80 kilometres per hour or above may affect Hong Kong. The heavy rain warning was issued when an hourly rainfall of more than 50 mm (2 inches before metrication) was expected in six hours. It is issued irrespective of whether they are widespread or isolated. Hong Kong braced for heavy rain and flooding as storm clouds gather “Though the rainstorm warning has been cancelled, people should … The public will be given clear advice on the appropriate actions to take. The Hong Kong Observatory issues the warning signal if a tropical cyclone approaches within 800 kilometres (500 mi) of Hong Kong and poses a threat of deteriorating conditions in Hong Kong. A warning of landslips will be issued by the Observatory in consultation with the Geotechnical Engineering Office whenever landslips are considered to be likely as a result of heavy rain which has occurred and is expected to continue in the next few hours. Thunderstorm warning issued by Hong Kong Observatory. A Landslip Special Announcement is broadcast by radio and television stations to the public.

It will be valid until 7:30 p.m. today.

Thunderstorms commonly occur in spring and summer months in Hong Kong. The Hong Kong Observatory has issued the thunderstorm warning at 2:00pm and it will be valid until 5:00pm today as squally thunderstorms are expected to occur over the city. A digest of the information is also made available to radio and television stations, and given in the Observatory's Dial-a-Weather system. When the Amber Rainstorm Warning Signal is issued, it gives alert about potential heavy rain that may develop into Red or Black Rainstorm Warning Signal situations. A few squally thunderstorms are expected to occur over Hong Kong.

Members of the public should be on the alert. On average, thunderstorms are reported at the Hong Kong Observatory about 5 days per month during April to September.In 2005, the Hong Kong Observatory set up a lightning location network in cooperation with the Guangdong Meteorological Bureau and the Macao Meteorological and Geophysical Bureau. A special announcement of flooding due to heavy rain in the northern New Territories will be issued by the Observatory whenever significant flooding is expected to occur or is already occurring in the low-lying plains of northern New Territories. The announcement indicates the affected districts and the respective rainfall recorded to alert the public.

When heavy rain is recorded in individual districts of Hong Kong and may bring serious flooding and risks to the districts, the Observatory will issue the Announcement on Localised Heavy Rain.