Tracking to the west northwest, Meranti gradually intensified until September 11, at which point it began a period of rapid intensification.

Meranti passed to the south of Taiwan as a super typhoon, and began weakening steadily as a result of land interaction.

Upon moving inland, rapid weakening ensued and Meranti became extratropical the next day, dissipating shortly afterwards after it passed to the south of the Korean Peninsula.

On September 8, the Joint Typhoon Warning Center (JTWC)[nb 1] issued a Tropical Cyclone Formation Alert for an area of convection about 155 km (96 mi) west of Guam in the western Pacific Ocean.

By that time, the nascent system was moving slowly west-northwestward through a region of low wind shear, steered by ridges to the north and southwest.

[14] At 06:00 UTC on September 12, the JTWC upgraded Meranti to a super typhoon, with 1-minute maximum sustained winds of 240 km/h (150 mph).

[15] Six hours later, the JTWC estimated 1-minute sustained winds of 285 km/h (180 mph), equivalent to Category 5 on the Saffir–Simpson scale, while noting "an extremely favorable environment", and that the eye became even more symmetric within intense convection.

[16] Outflow enhanced by a strong anticyclone over Meranti fueled the intensification,[17] and the typhoon peaked in intensity on September 13 while passing through the Luzon Strait.

[20] Late on September 13, the storm made landfall on the 83 km2 (32 sq mi) island of Itbayat in the Philippine province of Batanes shortly after attaining its peak intensity, with 1-minute sustained winds of 305 km/h (190 mph).

[21][22] A weather station on the island measured 10-minute sustained winds of 180 km/h (110 mph) and a concurrent pressure of 933.6 mbar (27.57 inHg) around 17:00 UTC before being destroyed.

[26] From text messages received by family members, residents in Itbayat reported their stone homes to be swaying during the height of the typhoon.

[32] In Fujian, the cities of Xiamen, Quanzhou and Zhangzhou were left paralyzed in Meranti's wake,[33] while flash floods in Yongchun County destroyed an 871-year-old bridge that was classified as a protected heritage site.