On this topic, Philippines disaster agency Executive Director Ricardo Jalad said, "residents in coastal areas must be evacuated by Thursday [today], when heavy rains are expected".
It packs maximum sustained winds of 205 kilometers per hour (kph) and gustiness near the center of up to 255 kilometers per hour (kph).
Cathay Pacific Airways Ltd. encouraged passengers travelling this weekend to and from Hong Kong to re-book and the airline will waive the fees.
The International Federation of Red Cross and Red Crescent Societies is predicting Mangkhut will leave "substantial damage" in its path.
A powerful typhoon is expected to make a landfall in the Philippines' main Luzon island on Saturday (Sept 15), prompting authorities to place 17 areas on alert and start evacuations.
Up to 43.3 million people from Guam, Northern Mariana Islands, the Philippines and China could be affected by the super typhoon, according to the Global Disaster Alert and Coordination System.
The typhoon is expected to boost the intensity of seasonal monsoon rains that have already caused widespread flooding in central Luzon, a mainly farming region north of capital Manila.
The storm, named after a fruit in Thailand, is forecast by the USA military's Joint Typhoon Warning Center to bring top winds of 145 knots (268 kilometers per hour) with maximum gusts of 175 knots.
About 80 per cent of the USA territory was without power but it was restored by Thursday morning.
He said classes in schools would be suspended on Thursday and offices, except those involved in rescue and relief work, would be advised to close on Friday.
Luzon was devastated by Super Typhoon Haima - known as Lawin locally - in 2016, with 14,000 houses destroyed and 50,000 homes damaged, according to CNN Philippines.
"I'm stressing that this one is very different, this is more complicated because of possible storm surges", Mamba said, referring to giant waves whipped inland by a typhoon. The threat to agriculture comes as the Philippines tries to cope with rice shortages.
In Hong Kong preparations are already under way for the storm, although it is not expected to hit until Sunday.
An average of 20 typhoons and storms batter the country each year, leading to hundreds of deaths.
Meanwhile, the USA east coast braces as Hurricane Florence barrels towards the Carolinas, expected to make landfall late September 14 or early September 15.