Tropical Storm Mirinae unleashed severe flooding in parts of central Vietnam, killing 11 people, while the death toll in the Philippines rose to 19.
Floods in Vietnam's Phu Yen province killed 10 people after the storm hit, drenching the region with heavy rains on Monday, said disaster official Duong Van Huong.
Several villages in neighbouring Binh Dinh province suffered the worst flooding in four decades after the Ha Thanh River surged over its banks, said disaster official Nguyen Van Hoa.
In the Philippines, the National Disaster Coordinating Council said the deaths were due mostly to drowning and occurred in suburban areas just south of Manila and in two eastern provinces.
The death toll is 19 with almost 16,000 people still in evacuation centres three days after the typhoon hit.
Floodwaters remain waist-deep or higher in Laguna province south of Manila and in Pangasinan to the north, after Mirinae dumped more rain on areas already inundated by two previous deadly storms.
In Vietnam local authorities asked the central government to send helicopters to rescue people who were still trapped on rooftops a day after the storm, which lost force as it moved inland.
"We have received many calls for help from people who are still stranded," disaster official
Duong Van Huong.
Soldiers in speedboats navigated to submerged areas and ferried out residents.
Mirinae hit the Philippines with typhoon strength over the weekend before losing strength as it moved across the South China Sea toward Vietnam.