On August 17, an area of circulation within the monsoon trough located in the Philippine Sea became more organized and the JTWC issued a TCFA.

The storm passed over the north of the island on August 20 and entered the South China Sea, reaching typhoon strength the next day.

Sam gradually intensified further as it approached the Chinese coast and it made landfall about 19 km (12 mi) to the northeast of Hong Kong at its peak with 140 km/h (85 mph) winds on August 22.

The heavy rain led to many instances of flooding and over 150 landslides throughout Hong Kong, killing 1 person and forcing the evacuation of about 1,000.

[5] In addition to the direct casualties from the storm, China Airlines Flight 642, using an MD-11 aircraft, crashed while attempting to land at Hong Kong International Airport, killing three on board and injuring 219.