The death toll in the Philippines from Typhoon Kalmaegi rose to 114 with another 127 people still missing, the disaster agency said on Thursday, as the storm that devastated the country's central regions regained strength as it headed towards Vietnam.

In Vietnam's Gia Lai province, some 350,000 people were expected to have been evacuated by the middle of the day as authorities warned of heavy rains and damaging winds that could cause flooding in low-lying areas and disrupt agricultural activity.

In the Philippines' hardest-hit province of Cebu, the scale of the destruction became clearer as floodwaters receded to reveal flattened homes, overturned vehicles and streets choked with debris.

More than 200,000 people were evacuated in the Philippines ahead of Kalmaegi hitting on Tuesday. Some have returned to find their homes destroyed, while others have begun the arduous cleanup, scraping mud from their houses and streets.

"The challenge now is debris clearing... These need to be cleared immediately, not only to account for the missing who may be among the debris or may have reached safe areas but also to allow relief operations to move forward," Raffy Alejandro, a senior civil defence official, told DZBB radio.

New storm developing

Even as Typhoon Kalmaegi, locally named Tino, exited the Philippine monitoring zone, weather forecasters were tracking a brewing storm east of Mindanao that could strengthen into a typhoon, raising concerns for potential impacts early next week.

The devastation from Kalmaegi, the 20th storm to hit the Philippines this year, comes just over a month after a magnitude 6.9 earthquake struck northern Cebu, killing dozens and displacing thousands.

As Kalmaegi moved over the South China Sea ahead of its landfall in Vietnam, it was regaining strength. It is forecast to impact several central provinces, including key coffee-growing areas, where the harvest season is currently underway.

Authorities were mobilising thousands of soldiers to assist with potential evacuations, rescue operations, and recovery efforts.

Vietnam's aviation authorities said operations at eight airports, including the international airport in Da Nang, are likely to be affected. Airlines and local authorities have been urged to closely monitor the storm's progress to ensure passenger safety.