Cecil originated from an area of convection that tracked west-northwest and passed south of Palau late on October 9.

Cecil turned northwest over the open waters of the South China Sea as it steadily strengthened, and was classified as a typhoon on October 14.

After unexpectedly slowing down, Cecil continued to intensify and at noon of October 14, reached its peak intensity of 145 km/h (90 mph).

Typhoon Cecil was considered the worst natural disaster in the central portion of the country in history.

At 02:22 UTC on October 11, a Hurricane Hunter aircraft discovered a surface circulation east of Mindanao along with winds of 30 to 40 km/h (20 to 25 mph) and a barometric pressure of 1,006 mbar (29.7 inHg).

[2][nb 1] Early on October 12, the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert for the system.

At the time, the JTWC expected the cyclone to rapidly intensify over the South China Sea and strike Vietnam within three days.

[1] The JMA set the peak intensity at noon on October 14, with winds of 145 km/h (90 mph) and a minimum pressure of 960 mbar (28 inHg).

Continuing to slowly track northwest as the ridge to its north was weaker than expected, Cecil passed south of Hainan Island that morning and, according to the JTWC, began to weaken due to its close proximity to Vietnam.

Cecil crossed into Laos two hours later and by 06:00 UTC on October 16, the JTWC ceased tracking the system.

The European Economic Community awarded $112,676 in cash while Secours Populaire Français donated $139,188, along with 50 t (55 short tons) of iron nails, 23,200 bottles of Ampicillin, and 1,000 bags of salt.

The British Red Cross provided $60,000 while the United States–based Vision International contributed $50,000 worth of clothes, medicine, and building material.