Betty turned westward, where it rapidly intensified before attaining peak intensity on August 11.

The origins of Typhoon Betty can be traced back to a tropical disturbance that was embedded in the monsoon trough on August 7, which extended from the Marshall Islands westward to the Philippines.

Intensity estimates via the Dvorak technique yielded winds of 50 km/h (30 mph) around 65 km (40 mi) north-northwest of Belau in the western Caroline Islands.

Following a rapid increase in organization, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert (TCFA) for the system early on August 8.

[3][nb 1] Around this time, the Philippine Atmospheric, Geophysical and Astronomical Services Administration also monitored the storm and assigned it with the local name Herming.

[6][nb 2] Betty continued to intensify, and by midday, the storm attained winds of 80 km/h (50 mph).

[3] At 0000 UTC on August 10, both the JMA and JTWC believed that Betty attained typhoon intensity.

[6] Tracking westward Betty began an episode of explosive deepening as expected by the JTWC.

[6] Later that day, the JMA estimated that Betty attained its peak maximum sustained wind of 190 km/h (120 mph) and a minimum barometric pressure of 890 mbar (26 inHg).

This concluded the storm intensification period; according to the JTWC, Betty strengthened 93 mbar (2.7 inHg) in a 37-hour time frame.

[2] At peak, which it maintained for 12 hours,[6] Betty exhibited a small but well-defined eye surrounded by very cold cloud tops.

[3] On the morning of August 14, the JTWC remarked that Betty reached its secondary peak intensity of 210 km/h (130 mph).

After entering the Gulf of Tonkin, Betty made landfall 350 km (215 mi) south of Hanoi in northern Vietnam on August 16.

[3] It then swept across Laos and eventually dissipated over northern Thailand near Chiang Mai during the evening of August 17.

[19] Along the Maguindanao and Albay provinces, 10,000 people were evacuated[14] and crop damage totaled $50,000;[11] in the latter alone, 1,000 families were displaced.

[24] Along southern Luzon, railway service was suspended and 11 domestic flights in and out of the country on August 12 were cancelled.

[31] Following the storm, Philippine President Corazon Aquino declared a state of calamity in more than a dozen provinces.

[32] Within a few days after Betty hit, the Philippine Airlines resumed normal flight schedules and schools were reopened.