“The NCR is in greatest danger here,” Interior Minister Juanito Victor Remulla said at the briefing. “NCR is very vulnerable to flooding again.”

Man-yi strengthened overnight in the western Pacific, with sustained winds of up to 150 km/h and gusts of up to 185 km/h. It is expected to make landfall in eastern Catanduanes province between Saturday night and Sunday morning.

Another typhoon, Usagiweakened sharply on Friday after lashing the northern cities of the Philippines, blowing away houses in its path before heading towards Taiwan.

No casualties have yet been reported from Usagi but thousands of families living in vulnerable communities have fled ahead of its arrival.

Rueli Rapsing, director of the Cagayan Disaster Relief Office, said city officials are still checking the extent of damage from the storm.

“There were more homes that were completely or partially blown after Marce (Typhoon Yinxing). Currently, we are moving around and assessing the damage,” Rapsing said on Friday.

Mandatory evacuations of vulnerable residents in coastal cities along the path of Typhoon Man-yi will begin on Friday, the Interior Ministry said.

In October, Tropical Storm Trami and Typhoon Kong-rey brought heavy flooding and triggered landslides, killing 162 people with 22 still missing, according to government data.

Four storms hit the western Pacific at the same time this month, the first time that has happened since records began in 1951, the Japan Meteorological Agency said.

About 20 tropical storms hit the Philippines every year on average, bringing heavy rains, strong winds and deadly landslides.

In 2013, Typhoon Haiyan, one of the strongest typhoons ever recorded, struck the central city of Tacloban, killing more than 6,300 people.

Storms have become stronger and draw energy from warmer waters, while rising sea levels also make low-lying coastlines more vulnerable.