It intensified on May 23 and became a tropical depression, giving it the name Aghon by the Philippine Atmospheric, Geophysical, and Astronomical Services Administration after entering the Philippine Area of Responsibility, marking it as the fifth-latest start of a Pacific typhoon season since reliable records began; the depression intensified into a tropical storm, assigning it the name Ewiniar.

Beginning to weaken for the final time on May 30, the storm passed directly over the island of Minamidaitōjima and began an extratropical transition.

In Japan, heavy rainfall was observed in several regions, with a maximum of 52.5 mm (2.07 in) of rain being recorded in Miyake, Tokyo.

The disturbance was moving northwestward towards an environment favorable for tropical cyclogenesis, characterized by sea surface temperatures of 29–30 °C (84–86 °F), low vertical wind shear, and moderate to strong outflow aloft associated with an upper tropospheric trough west of the system.

[4] At 18:00 UTC on May 23, the JMA identified the system as a tropical depression,[5] and later that day, it entered the Philippine Area of Responsibility (PAR).

[7] Early morning of May 24, the Philippine Atmospheric, Geophysical and Astronomical Services Administration upgraded the system from a low-pressure area into a depression, assigning it with the name Aghon — a Hiligaynon word for a mariner's compass and the replacement name for Ambo — marking it as the fifth-latest start of a Pacific typhoon season since reliable records began.

[15] In the morning of May 26 (PHT), the storm made its 8th landfall over Lucena, Quezon in Luzon island;[16] nonetheless, the system developed a small dense overcast holding a ragged, formative eye.

[21] Soon after, the JMA upgraded Ewiniar to a severe tropical storm at 06:00 UTC on May 26 as its maximum sustained winds increased to 100 km/h (65 mph).

[27] On May 27, the JMA recorded maximum sustained winds of 130 km/h (80 mph) and a minimum barometric pressure of 970 hPa (28.64 inHg) as the system's peak intensity.

[6] The storm then deteriorated from subsidence from a mid-latitude trough aloft as evidence by the structure's erosion and warming cloud tops.

[6] Environmental conditions became more unfavorable as sea surface temperatures decrease and vertical shear increases, as dry air invaded the system from the lower troposphere.

[33] On May 30, the JTWC reported that Ewiniar had begun losing its tropical characteristics while 719 km (447 mi) east-northeast of Kadena Air Base in Okinawa, Japan.

[35] The storm then developed a cold front to its southwest as deep convection detached from the fully-exposed and asymmetrical center, briefly becoming a subtropical cyclone.

[37] The JTWC then ceased issuing advisories on the system the next day as it entered the baroclinic zone and an area of high wind shear.

1 alerts from the eastern portions of Bulacan, Nueva Ecija, Quezon, Laguna, Rizal, and Romblon, and the entirety of Aurora, Marinduque, Camarines Norte, Masbate, Eastern Samar, Southern Leyte, Bohol, Dinagat Islands, Agusan del Sur, and Agusan del Norte.

3, indicating an expectation of winds of 89–117 km/h (55–73 mph) within the next 18 hours for the eastern section of Quezon, including the Polillo Islands, while storm signals were also raised in Metro Manila and parts of Bataan, Batangas, Pampanga and Oriental Mindoro.

[46] Classes and government work in some parts of Metro Manila, Aurora, Laguna, Quezon, Batangas, Cavite, and Nueva Ecija were suspended due to the typhoon.

[48] The Japanese government issued a high alert as Ewiniar was likely to enhance a stationary front near the nation, which would cause heavy rainfall throughout Japan.

[53][54] Some flooding occurred in Misamis Oriental,[55] Eastern Visayas, and Bicol on May 25, causing a tree in Legazpi, Albay to fall down and injure three people.