Schools were closed and thousands of people were evacuated across the north of the Philippines' main island of Luzon ahead of the strongest storm to pummel the country this year, rescue and relief officials said.

The northeastern provinces of Isabela and Cagayan were the first to feel the typhoon's fury on Monday morning, chief government weatherman Graciano Yumol said in an interview with GMA 7 television.

In the northern city of Tuguegarao in Cagayan, a man drowned in a river while fishing, the nation's civil defence chief, Benito Ramos, told reporters in Manila. Television footage showed motorized tricycles overturned and tin roofing blown away by the strong winds in Isabela.

The storm, dubbed a "super-typhoon" by government relief agencies, was packing gusts of up to 260 kilometres per hour, the government weather station said.

Megi was expected to dump heavy rain across the northern part of Luzon throughout Monday, then head toward southern China on Tuesday, according to the weather station.

AFP