The Philippines issued fresh weather warnings on Tuesday as the fifth major storm in three weeks bore down on the archipelago, days after thousands were evacuated ahead of Typhoon Toraji.

Now a weakened tropical storm, Toraji blew out to sea overnight after causing relatively limited damage and no reported deaths.

But Tropical Storm Usagi is now just two days away from the coast of Luzon, the archipelago nation's largest and most populous island, and gaining strength, the national weather agency said.

The government said it had evacuated more than 32,000 people from vulnerable areas in the northern Philippines ahead of Toraji's Monday landfall, weeks after Severe Tropical Storm Trami, Typhoon Yinxing and Super Typhoon Kong-rey killed a combined 159 people.

Most of that tally came during Trami, which unleashed torrential rains that triggered deadly flash floods and landslides.

The government did not report substantial flooding caused by Toraji and has so far not called for evacuations ahead of Usagi's arrival.

"Areas in northern Luzon are at risk of heavy rainfall, severe wind, and, possibly, storm surge inundation from (Usagi) which may cause considerable impacts," the weather service said in a fresh bulletin, using a term for giant coastal waves.

Usagi has strengthened to 85 kilometres (53 miles) an hour and may start affecting the region late in the day and reach typhoon category by Wednesday, a day ahead of landfall, it added.

Coastal waters will be rough and "mariners of small seacraft... are advised not to venture out to sea under these conditions".

While the government reported no casualties from Toraji, it said around 15,000 people were still sheltering at mainly government-run evacuation centres.

Utility workers on Tuesday repaired damaged bridges, restored electricity and cleared roads blocked by landslides, fallen trees and power pylons, the civil defence office said.

The full extent of the damage to private homes was not immediately known, but 29 towns and cities were still without power even as ports reopened and young people in nearly 600 towns and cities began returning to class.

"A small number of people were preemptively evacuated but they have since returned home. Classes at the collegiate level have resumed," civil defence official Randy Nicolas of Ilocos Norte province on Luzon's South China Sea coast told AFP.

After Usagi, the weather service said Tropical Storm Man-yi, currently near the Northern Mariana Islands, may also threaten the Philippines next week.

About 20 big storms and typhoons hit the archipelago nation or its surrounding waters each year, killing scores of people and keeping millions in enduring poverty.

A recent study showed that storms in the Asia-Pacific region are increasingly forming closer to coastlines, intensifying more rapidly and lasting longer over land due to climate change.