The Observatory on Tuesday issued the Standby Signal No. 1, saying it will remain in force before 10 am.
The signal was issued at 3.45 am with the Observatory saying that, according to its present forecast track, the tropical depression would remain at a distance of over 500 kilometres from Hong Kong in the morning.
It said it would consider issuing the Strong Wind Signal No. 3 later, depending on the changes in local winds.
The Observatory said the outer rain bands of the tropical depression would affect Hong Kong on Tuesday and that there would be squally showers and thunderstorms, with showers being heavy at times.