As the development of thunderstorms can be fairly rapid and localised, this warning is to draw particular attention to thunderstorms that are about to or are taking place, whether previously expected or not.
This warning is issued whenever ground frost is expected to occur on high ground or inland in the New Territories.
A Special Announcement on Flooding in the northern New Territories is issued whenever flooding induced by heavy rain is expected to occur or is occurring in the low-lying plains of the northern New Territories.
A fire danger warning is issued whenever the relative humidity of the atmosphere falls below certain criteria and the vegetation is dry. A yellow fire danger warning indicates that the fire risk is high, while a red fire danger warning indicates that the fire risk is extreme.
A landslip warning is issued by the Hong Kong Observatory in conjunction with the Geotechnical Engineering Office when persistent heavy rainfall results in a high risk of numerous landslips occuring.
Hong Kong experiences both hot and cold seasons, and the Observatory maintains a close watch on local temperature changes. Warnings are issued whenever Hong Kong is threatened by cold or very hot weather, so to alert members of the public of the danger of low body temperature and the risk of heatstroke respectively.
The Strong Monsoon Signal is issued when winds associated with the summer or winter monsoon are blowing in excess of or are expected to exceed 40 kilometres per hour near sea level anywhere in Hong Kong.
This warning is issued when a severe earthquake is expected to generate a tsunami that would reach Hong Kong within 3 hours, and the height of this tsunami may exceed 0.5 metre above the normal tide level.