The storm, named Enteng in the Philippines, caused severe flooding and landslides on Monday after crossing the island of Luzon with rain and sustained winds of 75km/h and maximum gusts of up to 90km/h.
In a meeting with President Ferdinand Marcos Jr the country's disaster management agency said among those missing are a group of 15 sailors whose ship sank.
At least 15 people are dead and 21 missing after Tropical Storm Yagi hit. (AP PHOTO)
Most fatalities were due to landslides, drowning or electrocution, while 15 people were injured by the effects of the storm.
More than 1.7 million people have been affected, of whom some 88,000 are displaced, and the estimated damage amounts to PHP350 million (almost $A9.3 million).
The storm also caused the cancellation of dozens of domestic flights and the suspension of classes in more than 450 educational centres.
Marcos asked authorities to focus on search and rescue operations, while work continues to clear roads and debris.
The Philippines suffers about 20 typhoons and tropical storms every year. (AP PHOTO)
Chinese authorities issued new alerts on Wednesday for Typhoon Yagi, the 11th this year, expected to make landfall between Wanning, on the island of Hainan, and Dianbai, in Canton, on Friday afternoon as a strong typhoon or super typhoon.
The Philippines suffers about 20 typhoons and tropical storms per year, especially in the rainy season, which usually begins in June and ends in November or December.
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