Tropical Storm Trami moved away from the north-western Philippines on Friday, leaving at least 82 people dead in extensive flooding.

A provincial police chief reported that 49 of the fatalities occurred mostly in landslides triggered by Trami in Batangas province, south of Manila, raising the overall death toll.

But the onslaught may not be over.

State forecasters raised the rare possibility that the storm, the 11th and one of the deadliest to hit the Philippines this year, could make a U-turn next week as it is pushed back by high-pressure winds in the South China Sea.

The storm was last tracked at dawn 125 kilometres west of Bacnotan, a coastal town in northern La Union province, with sustained winds of up to 95 kilometres per hour and gusts of up to 115kph.

It was moving north-west at 25kph toward Vietnam, which was forecast to be lashed by Trami starting on Sunday if it stays on course.

The Philippine weather agency, however, said it's possible that high-pressure winds and other weather factors in the South China Sea, could force the storm to turn back toward the Philippines.

President Ferdinand Marcos inquired about that prospect in an emergency meeting with cabinet members and disaster-response officials on Friday about the response to the widespread devastation.

"What is the forecast for that? Is it possible it would return?" Mr Marcos asked.

A government forecaster told him Trami could turn toward the western Philippines early next week, but it is more likely to blow away from the Philippines again without making landfall.

"It doesn't have to make landfall for the damage to occur," Mr Marcos said, citing the continuing downpours set off by Trami in the Philippines.

State forecaster Jofren Habaluyas said Trami's possible U-turn has drawn interest among government weather experts in Asia, including those from Japan, which has been providing information to the Philippines to help track the storm.

Trami dumped two months' of rainfall in 24 hours

The centre of the slow-moving storm hit Luzon island on Thursday with winds of nearly 100kph.

Although Trami did not strengthen into a typhoon, it dumped unusually heavy rains in some regions — including some that saw one to two months' worth of rainfall in just 24 hours — that inundated communities with flash floods.

Officials in Naga city, where 11 people died by drowning, and the outlying provinces of Camarines Sur and Albay, pleaded for more rescue boats at the height of the onslaught to reach people trapped on the upper floors of their homes or their roofs as floodwaters rose.

Five of the reported deaths came from floodwaters and landslides in Bicol, an agricultural region and tourism destination south-east of Manila.

Bicol is known as the home of Mayon, one of the country's 24 most active volcanoes that has a near-perfect cone.

In the foothills of the volcano in Albay province, mud and other debris cascaded toward nearby towns as the storm hit, engulfing houses and cars in black-coloured mudflows.

More than 2.6 million people were affected by the deluge, with nearly 320,000 people fleeing into evacuation centres or relatives' homes, disaster mitigation officials said.

Police said nine of the reported storm deaths were caused by flooding and landslides in Batangas, a coastal resort province south of Manila which was drenched by torrential rains in the last two days.

Nearly 240,000 people were sheltering in evacuation centres, with 7,510 passengers stuck in ports and 36 flights cancelled on Friday, the government said, as the president directed assistance to be sent to the worst-affected areas.

"I make this pledge to our people: Help is on the way. It will come by land, air, and, even by sea," Mr Marcos said on X.

The government shut down schools and government offices in Luzon. Inter-island ferry services were also suspended, stranding thousands.

In Talisay town two hours drive south of the capital, residents were starting to clean up. Some homes and cars are buried in waist-high soil and hardened mud, and debris is strewn over the streets.

"The rain was intense so no-one was able to prepare and many died," resident Romeo Albellar said.

"My house was completely destroyed and no items were saved. We are back to zero."

Vietnam prepares for Trami as another storm brews in the Pacific

Mr Marcos also cited another brewing storm in the Pacific Ocean that could again threaten the country.

"Oh God, it is what it is. We just have to deal with it," Mr Marcos said.

In Vietnam, state forecasters warned of heavy rains in the central region.

Prime Minister Pham Minh Chinh ordered coastal provinces to stay vigilant, closely monitor Trami's course and brace for contingencies.

Last month, Typhoon Yagi battered Vietnam, killing 323 people and causing extensive damages, according to a Vietnamese government report.

Each year, about 20 storms and typhoons batter the Philippines, a South-East Asian archipelago that lies between the Pacific Ocean and the South China Sea.

In 2013, Typhoon Haiyan, one of the strongest recorded tropical cyclones, left more than 7,300 people dead or missing and flattened entire villages.

AP/Reuters