[1] Over the next day the system's low level circulation centre started to consolidate as it moved westwards, before it was classified as a tropical depression by the Japan Meteorological Agency (JMA) during August 15.

[5][6] After being named, Dianmu continued to move westwards under the influence of a subtropical ridge of high pressure located to the north of the system and made landfall on China's Leizhou Peninsula.

[5][6] The system subsequently entered the Gulf of Tonkin later that day, where it developed an eye feature on microwave imagery, before it peaked with sustained winds of 75 km/h (45 mph) as it made landfall on northern Vietnam during August 19.

[3][6][7] Over the next day Dianmu gradually weakened as it moved westwards through Vietnam, Laos and China's Yunnan province, before it degenerated into an area of low pressure over northern Myanmar during August 20.

[8] Dianmu passed about 220 km (135 mi) to the southwest of Hong Kong, China during August 17, where it generated moderate to fresh easterly winds.