Moving quickly westwards, Son-Tinh strengthened to the ninth tropical storm of the annual typhoon season on July 17.

Accordingly, the Joint Typhoon Warning Center (JTWC) designated it as 11W while the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) gave it the local name Henry.

[14] Before making landfall in Northern Vietnam, the JMA reported that Son-Tinh reached peak intensity with 10-minute sustained winds of 75 km/h (45 mph) and a central pressure of 994 hPa (29.4 inHg).

Both the JMA and the JTWC issued their final warnings on Son-Tinh on July 19 as the system degenerated into an area of low pressure embedded in the monsoon.

[18] Persistent convection developed over the system, aided by a tropical upper tropospheric trough to the northeast, prompting the JTWC to begin issuing advisories on Son-Tinh once again on July 21.

[24] In Vietnam, the Thanh Hóa and Nghệ An provinces suffered the most damage, especially with the wake of the storm continuing to generate significant rainfall.