This means that heavy rain has fallen or is expected to fall generally over Hong Kong, exceeding 50 millimetres in an hour, and is likely to continue.
The Observatory warned further heavy rain could cause, if it has not already caused, serious road flooding and traffic congestion.
Students of AM schools and whole-day schools do not have to attend school today. Schools should keep their premises open and implement contingency measures to look after arriving students. Parents do not need to pick up their children from schools immediately.
People who have to travel should carefully consider the weather and road conditions and take necessary precautions.
Heavy rain will bring flash floods, and flooding is occurring or is expected to occur in watercourses. People should stay away from watercourses.
Residents living in close proximity to rivers should stay alert to weather conditions and should consider evacuation if their homes may become flooded.