The Observatory is considering hoisting the standby strong wind signal today, which if hoisted, will be the first typhoon warning to be issued in December in 47 years.
This came as tropical cyclone Rai moved north across the South China Sea's central region at a speed of 18 kilometers per hour and was centered around 280km southwest of Xisha, Hainan, at 8pm yesterday.
It is forecast to come within 800km of Hong Kong today at 140km per hour.
"Depending on the intensity and track of Rai, the Observatory will consider the necessity of issuing a tropical cyclone warning signal tomorrow," a spokesman said yesterday.
"The Observatory will closely monitor its development Members of the public should take note of changes in weather."
The spokesman noted that Rai will be the closest to the city tomorrow.
"On Tuesday, Rai will weaken into a tropical storm with the maximum gust near the tropical storm's center reaching 75km per hour."
He added that the tropical storm would further weaken into a tropical depression as it is expected to move north toward the Guangdong coast before heading to the Pratas Island on Wednesday. The weather for today will be cooler with occasional rain during the day and in the evening.
Temperatures will range between 15 and 19 degrees Celsius, with moderate to fresh northeasterly winds predicted to be occasionally strong offshore on high ground. Tomorrow, the weather is predicted to be cloudy, cool, windy and accompanied by the occasional rain. The Macau Meteorological and Geophysical Bureau said yesterday it might issue signal No 1 today.
The danger posed by Rai emerged yesterday after more than100 people in the Philippines were reported killed by Rai's battering.
Efforts to deliver water and food to the country's islands are being ramped up.
Rai smashed into the country Thursday as a super typhoon packing wind speeds of 195km per hour.
More than 300,000 people fled their homes and beachfront resorts as Rai ravaged the southern and central regions of the archipelago.
The storm knocked out communications and electricity in many areas, ripped off roofs, damaged hospitals, toppled concrete power poles and flooded villages.
Popular tourist destination Bohol so far reported 72 deaths. Ten people also reportedly died on the Dinagat Islands.
That takes the number of reported deaths to 108, making it one of the deadliest typhoons to hit the country in years.