Schools remained closed and electricity was down in swathes of the archipelago nation's biggest island after days of monsoon rains that have killed 25 and left eight missing across the country, according to the natural disaster agency.

In the west coast province of La Union, where Co-May arrived in the early hours, a family of four was rescued after being trapped on the second floor of their wooden home.

"They couldn't leave their house because the flood was waist-deep and they have children," said a rescue official who asked not to be named as they were not authorised to speak to media.

"Many had been calling us since early morning, but we were having challenges in responding because the rain and winds were so strong," they said, adding that a break in the downpour meant rescue operations were now in full stride.

In Bulacan province, just north of the capital Manila, AFP journalists saw entire villages submerged in waist-deep waters.

Lauro Sabino, 54, said he and his wife had evacuated their home in the morning after a frightening night of hard winds.

"It was as if my roof was being blown off. It was creaking. The rain poured the entire night," he said, adding they would sleep at a local market until flooding subsided.

"The same thing happens every time. There's no solution," agreed Mary Rose Navia, 25, a housewife whose husband was unable to go to work on Friday.

"The floodwaters are just getting deeper."

President Ferdinand Marcos on Thursday explicitly tied the recent flooding to climate change, saying his country had to accept this was the "new normal".

"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 in a televised cabinet briefing.

The storm, which was weakening as it made its way north by northeast, was expected to be gone from the Philippines by Saturday morning.