The fourth named storm of the 2018 Pacific typhoon season, Ewiniar developed as a tropical depression just east of Vietnam on June 2.

The system moved generally northwards over the South China Sea, before intensifying into a tropical storm near the Qiongzhou Strait on June 5.

Ewiniar proceeded to stall over the region as steering currents collapsed, making landfall over the Leizhou Peninsula and later over northern Hainan.

Ewiniar accelerated to the northeast on June 7 and moved back over open sea, allowing it to strengthen slightly and reach peak intensity with maximum sustained winds of 75 km/h (47 mph) and a central pressure of 998 hPa (mbar; 29.57 inHg).

Gusty winds felled trees and heavy rains caused flash flooding, while a waterspout was sighted near Cheung Chau.

Around this time, thunderstorm activity increased in coverage with the development of outflow channels;[8] as a result, the JMA upgraded the depression to Tropical Storm Ewiniar at 00:00 UTC.

This moved Ewiniar back over water and allowed it to restrengthen,[12] reaching peak intensity with maximum sustained winds of 75 km/h (47 mph) and a minimum pressure of 998 hPa (mbar; 29.57 inHg) at 06:00 UTC.

[4][3] Ewiniar then turned to the north-northeast as it began to interact with the Meiyu front,[13] before making a third landfall in Yangjiang, Guangdong, at 12:30 UTC June 7.

[11] Once inland, the system soon became embedded within the Meiyu front and the JTWC declared that Ewiniar dissipated as a tropical cyclone near midday on June 8.

[14][3] The JMA, however, continued to track Ewiniar as a tropical depression while the system turned back east and emerged over the South China Sea on June 10.

[20] Ewiniar brought heavy rain to South China and Jiangnan for seven days, affecting 211,200 people with floods and landslides.

[27] Ewiniar also spawned a tornado in Dali,[28] which blew off a market's 400 m2 (4,300 sq ft) roof and damaged three cars but caused no casualties.

[32] Authorities allocated ¥290,000 (US$44,000) of funds for disaster relief and distributed bottled water, food, tents, beds, and towels to displaced residents.

3 Strong Wind Signal was raised over the territory from June 7–8,[33] during which kindergartens and schools for children with disabilities were closed and bunker operations at the Port of Hong Kong were suspended.

[34][35] Fallen trees damaged vehicles and obstructed traffic, with one such incident in Sai Wan Ho resulting in an injury.

Periods of intense rain, peaking at 46 mm (1.8 in) in one hour on the morning of June 8, caused several instances of flash flooding.