An approaching tropical storm intensified into a typhoon expected to bring moderate to heavy rainfall and severe winds over a swathe of the main Luzon island.
The Philippines' disaster agency was on high alert on Saturday.
Typhoon Noru, with sustained winds of up to 120 km per hour (75 mph), was expected to intensify prior to landfall in Aurora or Quezon province on Sunday, the weather bureau said in its latest advisory.
Noru was also expected to affect the capital region and northern provinces that were hit by a cyclone last month, which caused floods and landslides and led to the deaths of three people.
"The highest emergency preparedness and response protocol have been activated" in several regions, including Metro Manila, the agency said in a statement.
Local governments have been advised to undertake pre-emptive evacuations of communities in high-risk areas, it said, as weather forecasters warned of flooding and landslides.
The weather bureau said Noru was moving westward and likely to emerge over the South China Sea by late Sunday or early Monday.
The Strait of Hormuz remains open to all shipping except vessels linked to "Iran's enemies", Iran's representative to the UN maritime agency was quoted as saying in Iranian media reports published on Sunday.
The Gulf Cooperation Council (GCC) has renewed its condemnation of continued Iranian attacks on member states, including the targeting of infrastructure and oil facilities, in flagrant violation of international law and a direct threat to regional security, stability and the safety of global energy supplies.
The Qatar Ministry of Interior has confirmed six people died during a helicopter crash into "regional waters" on Sunday - with search and rescue teams still searching for the body of the seventh and final crew member.
Japan could consider deploying its military for minesweeping in the Strait of Hormuz, a vital artery for global oil supplies, if a ceasefire is reached in the U.S.-Israeli war on Iran, Foreign Minister Toshimitsu Motegi said on Sunday.