Typhoon Co-May, upgraded from a tropical storm overnight, follows days of monsoon rains that have killed at least 19 people and left another 11 missing across the archipelago since July 18, according to the national disaster agency.

With maximum sustained winds of 120 kilometres (75 miles) per hour, the typhoon was expected to make landfall on the west coast in either La Union or Ilocos Sur province by Friday morning, the country's weather service said.

Marcos said on Thursday that climate change meant Filipinos needed to be thinking about how to adapt to a "new normal".

"This is not an extraordinary situation anymore... This will be our lives no matter what we do," he told a televised cabinet briefing, adding the country should plan for the long-term in addressing natural disasters.

"This is the way it's going to be as far as we know for... many decades to come, so let's just prepare," he said.

"We have to understand that the climate has changed, the rain patterns have changed," he added, pointing to recent devastating flooding in the US state of Texas.

Around 70 domestic and international flights in the Philippines were cancelled Thursday due to the storms, the civil aviation authority said.

The government later announced that classes across Luzon would remain suspended through Friday.

Tens of thousands were evacuated across Manila earlier this week by floodwaters that swamped some neighbourhoods in waist-deep water and left residents of nearby provinces stranded and in need of rescue by boat.

As of Thursday, at least several thousand people in Manila remained unable to return to their homes.

"We cannot send them home yet because it is still raining and some typhoons are still expected to affect the country," Ria Mei Pangilinan, a rescue coordinator in the capital, told AFP.

"There might be more (evacuees) if the rain does not stop."

Typhoon Co-May was about 105 kilometres off the country's west coast as of 8 pm (1200 GMT).