After passing through the island nation, the storm emerged into the South China Sea and slowly gained strength, earning the name Linfa on October 10 on approach to Vietnam.

On the next day, Linfa had reached peak strength and made landfall in Vietnam, marking the beginning of a devastating series of floods in the country and worsening the already active monsoon season.

According to post-analytic data by the Japan Meteorological Agency (JMA), Linfa developed as a weak tropical depression just to the east of Bicol Region, Philippines on 18:00 UTC of October 6.

[2] After crossing the Philippine archipelago of Luzon and entering the waters of the South China Sea, the Joint Typhoon Warning Center (JTWC) issued a tropical cyclone formation alert on October 9.

[5] After animated satellite imagery depicted a defined low-level circulation center (LLCC) along with flaring deep convection,[6] the JTWC followed suit on classifying the system as a tropical depression and began issuing advisories, giving the identifier of 17W.

Microwave imagery depicted continued wrapping of deep convection to its LLCC, which prompted the JTWC to increase Linfa's 1-minute sustained winds to 75 km/h (45 mph).

As the storm moved over land, its circulation rapidly deteriorated and became partially exposed; the JTWC issued their final advisory on Linfa on 06:00 UTC of October 11.

[2] In the Philippines, the precursor to Linfa brought moderate to heavy rain to parts of Luzon and Visayas, with the PAGASA warning of possible flash floods and landslides in the areas affected.

Shortly after Linfa had moved inland, the storm brought historic amounts of precipitation to Central Vietnam, the peak rainfall total having been 90.16 inches (2,290 mm) in A Lưới (Huế).

[27] Prior to the storm, the Ministry of Water Resources and Meteorology warned of river floods and advised to open irrigation gates as rainfall was expected to quickly intensify due to Linfa in Laos.