More than 10,000 evacuees sheltered in schools and evacuation centres in the Philippines on Monday as heavy rains and gale-force winds from Super Typhoon Ragasa lashed the country's far north.

The typhoon is gaining strength as it proceeds on a collision course with southern China.

In Taiwan, smaller-scale evacuations were also under way.

Maximum sustained winds of 215 kilometres per hour were reported at the storm's centre, with gusts reaching up to 265 kmh, the Philippines weather service said.

"I'm seeing from my house here that the high waves are crashing onto the shore," said Tirso Tugagao, a 45-year-old teacher in Aparri, a coastal town in northern Cagayan province. "I pray everyone will be safe."

Cagayan disaster chief Rueli Rapsing said his team was prepared for "the worst".

President Ferdinand Marcos Jr said on Facebook he was closely monitoring the situation and that all government agencies were "on alert to give help anywhere and whenever needed".

Taiwan's weather service predicted a chance of "extremely torrential rain" to the east of the island.

"Its storm radius is quite large, about 320 [kilometres]," it said.

"Although the typhoon's centre is still some distance away, its wide, strong wind field and outer circulation are already affecting parts of Taiwan." (AFP)