On 6:00 UTC on September 4, the Joint Typhoon Warning Center (JTWC) began tracking a low-pressure area far east of Luzon.

[1] As the disturbance was in a favorable environment with low vertical wind shear and warm SSTs of 29–30 °C (84–86 °F), the JTWC issued a Tropical Cyclone Formation Alert (TCFA) on the system a day later.

[4] Tracking northwestward due to the influence of a subtropical ridge,[5] on 18:00 UTC on September 5, both the JTWC and JMA recognized the system as a tropical cyclone, with the latter agency naming it Yun-yeung as according to them, it had gale-force winds at the time.

[4] Yun-yeung steadily intensified, and early on September 7, the JMA's surface observations and Dvorak intensity estimates revealed that it had peaked with 10-minute sustained winds of 70 km/h (45 mph).

[6][7] Due to a binary interaction with the remnants of Kirogi, Yun-yeung began to slow down and track slightly south, crossing into an environment with wind shear in excess of 70 km/h (45 mph).

[9] On September 8, Yun-yeung made landfall as a weak tropical depression along the northern shoreline of Suruga Bay, degenerating into a wave-like feature.

[1] When Yun-yeung was initially developing far from the Philippines, it with Haikui primarily enhanced the southwest monsoon, causing heavy rains in portions of Luzon.