[1] At 09:30 UTC on October 21, the Joint Typhoon Warning Center (JTWC) began to monitor an area of convection that was located approximately 95 nautical miles (176 km) to the southeast of Palau.

At the time, it had persistent deep convection over the southern side of its poorly-organized low-level circulation center, and was under a marginal environment of weak vertical wind shear and diffluent northeasterly flow.

[2] Three hours later, the Japan Meteorological Agency (JMA) designated the low as a tropical depression, before initiating advisories on the system early by the next day.

[6] Five hours later, the PAGASA started issuing advisories on the tropical depression, as it developed in the Philippine Area of Responsibility (PAR), assigning its local name Ofel.

[16] Upon emerging to the West Philippine Sea on October 25, Son-Tinh struggled to intensify, with the continued effects of land interaction in the eastern quadrant.

[17][18] Late on the same day, the JTWC noted that Son-Tinh had started to develop banding over its northern and southern peripheries, with deep convection wrapping to its center.

[19] At 06:00 UTC the next day, the JMA upgraded Son-Tinh to a severe tropical storm, as it continued westward under the influence of the subtropical ridge to its north, leaving the PAR.

[24][25] Son-Tinh then reached its peak intensity six hours later, as it rapidly intensified to a category 3-equivalent typhoon, while entering a hostile environment of moderate wind shear and strong westerlies to its north.

[12][31] The JTWC downgraded Son-Tinh to a tropical storm and issued their final advisory at 00:00 UTC on October 29, as it turned northeast while weakening from land interaction.

A cargo ship, called the ML Lady RP II, sank with around 1,200 sacks of copra near Zamboanga City at the height of the storm.