Typhoon Agnes, known in the Philippines as Typhoon Undang, was the fourth final tropical cyclone to affect the Philippines during the 1984 Pacific typhoon season. An area of disturbed weather developed near the equator and the Caroline Islands on October 28. Following an increase in organization, the cyclone was designated a tropical storm on October 31. After tracking northwest initially, Agnes turned west-northwest the next day, a course that the system would maintain for the rest of its lifetime. Agnes intensified into a typhoon on November 2, and on November 4, attained peak intensity. The storm then made landfall on Samar Island, part of the Philippines, at that intensity. The storm weakened over land, but re-intensified over the South China Sea; Agnes obtained a secondary peak intensity on November 6. The next day, Typhoon Agnes moved ashore Vietnam while still at typhoon intensity. The storm rapidly deteriorated over land and dissipated by November 8 over Thailand.
Typhoon Agnes was the final of a series of tropical cyclones to affect the Philippines that season, following June, Ike, and Warren. Agnes brought widespread damage to several provinces across the central section of the archipelago. In the Iloilo province, 230 people were killed and four others were injured. Provincewide, a total of 21 homes were flattened, resulting in 1,326 homeless people. Damage in the province amounted to at least $5 million. Approximately 20% of the rice crop was destroyed in Iloilo. In the Capiz province, 265 people died and property damage amounted $25 million (1984 USD). Around 80% of houses in Roxas, located in Capiz, were damaged and 100 people were killed. Throughout Panay Island, four hundred forty-eight fatalities were reported, at least eight people were injured, five bridges were destroyed, and thirty-five schools were demolished. A total of 4,014 homes were destroyed; consequently, over 24,000 people lost their homes. Across the Philippines, 895 people died due to Agnes, with 272 people listed missing and 2,526 others wounded. A total of 491,968 people were evacuated to shelter in 27 provinces. More than 200,000 homes were destroyed while 163,056 other dwellings were damaged. Damage in the country totaled $90.7 million, with $19.1 million from crops and $56.9 million from public infrastructure.
In Vietnam, the typhoon severely affected the rice harvest and winter crop cultivation. The Nam Định Province suffered the brunt of the typhoon, where 134 people died and 289 sustained injuries. There, 400 schools and 230 nurseries were flattened. Throughout the country, the storm destroyed of farmland.
Meteorological history
Typhoon Agnes originated from an isolated area of convection located near the equator on October 28. Satellite imagery indicated a possible low pressure area near 149° E. Although the disturbance was not attached to the monsoon trough, an upper-level anticyclone became situated aloft, providing the system with strong ventilation. Midday on October 30, the Joint Typhoon Warning Center (JTWC) started tracking the system, with the Japan Meteorological Agency (JMA) upgrading the system to a tropical depression on the same day. Late on October 31, shower activity increased drastically in both coverage and organization as the disturbance tracked northwest. Early the next day, the JTWC issued a Tropical Cyclone Formation Alert. Shortly thereafter, a Hurricane Hunter aircraft investigated the system and found winds of ; these winds were significantly higher than intensity estimates from the Dvorak technique. At 06:00 UTC on November 1, the JTWC issued its first warning on the system, upgrading it to a tropical storm and naming it Agnes. The JMA also classified Agnes as a tropical storm at this time.