In Hong Kong, heavy rains are marked by three signals: yellow, red, and black.

Yellow signals a moderate amount of heavy rain within a short period of time.

Red signals a higher level.

Black signals the highest level. Basically all offices will be closed and schools as well. it is dangerous to be in the outside.

You can look up exact information in the Hong Kong observatory website. Basically there were heavy rains and thunderstorms that morning, which postponed arrival and departure, and caused a chain effect down the road. The flight was late leaving HK an hour +...

Carfield