Brendan quickly intensified to reach the first peak intensity of 115 km/h (70 mph) when it made landfall in Luzon, Philippines.

[nb 1] After emerging in Luzon Strait as a strong tropical storm and continued to track west-northwestward, Brendan reached the secondary peak intensity of 105 km/h (65 mph) in July 23, before making landfall on Guangdong, China, 30 kilometres (19 mi) southwest of Macau in July 24.

Across the Philippines, heavy rain associated with Brendan combined with volcanic debris from Mount Pinatubo raised mudflows up to 5 metres (16 ft) high around the vicinity of volcano.

Two fishermen from China reported missing southwest of Macau after the storm capsized their boats.

The circulation would track west-northwest for several days until it reached an area of increased upper-level divergence in the central Philippine Sea on July 19, leading JTWC to issue Tropical Cyclone Formation Alert at 18:00 UTC, when the system was located approximately 450 km (280 mi) east of Samar.

[2][nb 3] However, due to diurnal fluctuations that affected the system's convection, JTWC reissued the TCFA at 18:00 UTC on August 20, 1991.

Coupled with a low shear environment and warm sea surface temperatures, JTWC declared the system a tropical depression in the 00:00 UTC of August 21.

[2][nb 4][5] Across the Philippines, heavy rain associated with Brendan combined with volcanic debris from Mount Pinatubo raised mudflows up to 5 metres (16 ft) high around the vicinity of volcano.

Two fishermen from China reported missing southwest of Macau after the storm capsized their boats.