Originating from an area of low pressure near Wake Island on July 9, the precursor to Ma-on gradually developed as it moved westward.

Favorable environmental conditions allowed for additional strengthening, and the storm ultimately attained peak ten-minute sustained winds of 175 km/h (109 mph) on July 16.

The system ultimately became extratropical on July 24, and was last noted by the Japan Meteorological Agency a week later near the Kamchatka Peninsula.

Initially, Ma-on posed a slight threat to the Mariana Islands and prompted the issuance of tropical storm warnings.

[2] Early on July 11, the Joint Typhoon Warning Center (JTWC) issued a tropical cyclone formation alert,[3] and a few hours later the Japan Meteorological Agency (JMA) reported the formation of a tropical depression about halfway between Wake Island and the Northern Marianas Islands.

[14] Late on July 15, Ma-on weakened slightly due to stronger wind shear, which caused its eyewall to break apart in the northwest quadrant.

[16] At 0600 UTC on July 16, the JMA estimated peak 10-minute sustained winds of 175 km/h (109 mph) while the typhoon was located about 1,185 km (736 mi) southeast of Okinawa.

[17] Around that time, Ma-on began a motion to the northwest due to a weakening of the subtropical ridge,[18] and it briefly entered the area warned by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA); the agency gave it the local name Ineng.

[19] Late on July 17, Ma-on underwent another eyewall replacement cycle and weakened, despite developing improved outflow and convection in the northern quadrant.

[20] The typhoon's large size prevented re-intensification – gale force winds extended 370 km (230 mi) east of the center.

Turning to the east, the typhoon weakened to a severe tropical storm before moving over the southern tip of the Kii Peninsula early on July 20.

[31] High waves in advance of the typhoon capsized a boat in the East China Sea, although the six passengers were rescued.

[35] Before the storm struck Japan, officials in Miyakonojō, Miyazaki advised the evacuation of about 900 people in areas prone to mudslides.

[41] High rains closed several expressways, and in Shizuoka Prefecture, a blocked road stranded 96 mountain climbers.