Although the storm itself caused significant damage, the worst effects were related to the system's heavy rains mixing with volcanic ash from Mount Pinatubo, creating massive lahars that killed 320 people.

Situated to the southwest of a tropical upper tropospheric trough, the system experienced low wind shear and gradually intensified as it moved northwestward.

[2][nb 2] At 15:00 UTC on June 12, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert on the depression.

At 18:15 UTC, the USNS Spica sailed directly through the storm, measuring a barometric pressure of 989.5 mbar (hPa; 29.22 inHg) and peak winds of 110 km/h (70 mph).

Around 00:00 UTC on June 15, Yunya made landfall just north of Dingalan Bay as a minimal typhoon and weakened to a tropical storm shortly thereafter.

As the storm moved across Luzon, Mount Pinatubo, a volcano in the Zambales Mountains on the island's western side, was experiencing a major eruption—the second-largest to occur during the 20th century.

Due to Yunya's circulation, the massive cloud of ash produced by the eruption was moistened and redistributed over the Philippines instead of blowing out to sea, greatly exacerbating the impact of the event.

Having turned north within a break in the subtropical ridge, Yunya brushed the southern tip of Taiwan late on June 16 before dissipating the following day within the westerlies.

[1] On June 14, the Philippine Atmospheric, Geophysical and Astronomical Services Administration raised storm warnings in advance of Typhoon Yunya for much of Luzon and areas south of Manila.

[8] The wind from the typhoon carried ash within 160 km (100 mi) from Pinatubo, including to Manila,[10] which prompted most of the airports in the country to close and Philippine Airlines to cancel all domestic and international flights through June 19.

[11] Low to mid-level winds and heavy rains from the storm contributed to widespread tephra falling over an area of 7,500 km2 (2,895 sq mi) of central and western Luzon.