Around 6,000 at-risk residents have been ordered to leave the island Taal Volcano is on.
Tens of thousands more from nearby coastal towns have also been evacuated, officials said.
About 300,000 people were targeted to be moved to safety in nearby Batangas overnight and in the next few days.
The volcanology institute reminded the public that the small island where the volcano lies is a permanent danger zone, although fishing villages have existed there for years.
According to the National Disaster Risk Reduction and Management Council, a nine-mile high plume of volcanic ash has triggered ashfall in communities living nearby.
Renelyn Bautista, 38, was among thousands of residents who fled from Batangas province’s Laurel town. She said she hitched a ride to safety from her home with her two children, including a four-month-old baby:
“We hurriedly evacuated when the air turned muddy because of the ashfall and it started to smell like gunpowder.”
Heavy ashfall, including steam and pebbles, has also reached further afield – residents in the nearby province of Cavite are being warned to stay indoors.
Aviation officials also ordered the closure of Clark International Airport north of Manila after ash fell in the area.
The Philippine Institute of Volcanology and Seismology raised the alert level to level four on Sunday, just one below the highest possible alert level.
Authorities are warning level 4 indicates “a hazardous eruption may happen within hours or days”.
One of the world’s smallest volcanoes, Taal is among two dozen active volcanoes in the Philippines, which lies along the so-called Pacific Ring of Fire, a seismically active region that is prone to earthquakes and volcanic eruptions.
About 20 typhoons and other major storms each year also lash the Philippines, which lies between the Pacific and the South China Sea, making it one of the world’s most disaster-prone countries.