Philippine authorities have begun evacuating thousands of people in the path of the most powerful typhoon of the season, closing schools, readying bulldozers for landslides and placing rescuers and troops on full alert in the country's north.

Key points: Typhoon Mangkut has recorded winds of 265kph

Typhoon Mangkut has recorded winds of 265kph Potential for storm surges, flooding and landslides increase the risks

Potential for storm surges, flooding and landslides increase the risks The typhoon is the 15th storm to batter the Philippines this year

Forecasters said Typhoon Mangkhut could hit northern Cagayan province on Saturday.

More than four million people live in areas at most risk from the storm, which the Joint Typhoon Warning Center in Hawaii has categorised as a super typhoon with powerful winds and gusts.

On Thursday it was tracking about 725 kilometres away from the Philippines, with sustained winds of 205 kilometres per hour and gusts of up to 255 kph, Philippine forecasters said.

It could maintain the strength of a super typhoon when it hits land in the north-eastern corner of Luzon Island, which is home to about 48 million people.

With a massive rain band 900 kilometres wide, combined with seasonal monsoon rains, the storm could bring heavy to intense rains that could set off landslides and flash floods, state forecaster Meno Mendoza said.

Cagayan Governor Manuel Mamba said evacuations of residents from risky coastal villages and island municipalities north of the rice-and corn-producing province of 1.2 million people had started, and school classes at all levels had been cancelled.

"The weather here is still good but we're moving them now because it's very important that when it comes, people will be away from peril," said.

In 2016, a super typhoon lashed the southern section of Cagayan, destroying tens of thousands of houses.

Mangkhut is blowing from the Pacific and forecast to directly slam the province's north-eastern coastal and island municipalities, Mr Mamba said.

"I'm stressing that this one is very different — this is more complicated because of possible storm surges," Mr Mamba said, referring to giant waves whipped inland by a typhoon.

Workers remove an advertising billboard in Quezcon City in preparation for Typhoon Mangkhut. ( Reuters: Erik De Castro )

Harvest threatened amid rice shortages

The typhoon is arriving at the start of the rice and corn harvest season in Cagayan, a major agricultural producer, and farmers were scrambling to save what they could of their crops, Mr Mamba said.

The Philippines has been trying to cope with rice shortages.

Office of Civil Defence chief Ricardo Jalad said other northern provinces will also start evacuating residents from low-lying areas.

"The worst cases are those areas which will be directly hit by strong winds that can topple houses, storm surges and heavy rains that can cause flooding, and there may be landslides in higher areas," Mr Jalad said.

After leaving the Philippines, the fast-moving storm is expected to blow toward Hong Kong and southern China on Sunday if it maintains its course, forecasters said.

Mangkhut is the 15th storm this year to batter the Philippines, which is hit by about 20 a year and is considered one of the world's most disaster-prone countries.

Typhoon Haiyan left more than 7,300 people dead or missing and displaced more than five million in the central Philippines in 2013.

AP