Across the 10 provinces hit by flooding, more than 3.8 million people have been affected, the government said on Saturday.
The death toll from flooding and landslides on Indonesia's Sumatra island has risen dramatically to 417, officials say.
The total passed 300 earlier on Sunday, with evacuation efforts under way, major roads cut off, and internet and electricity only partially restored.
Monsoons exacerbated by tropical storms have caused some of the worst flooding in years across South East Asia.
Hundreds are dead and missing in Malaysia and Thailand as well, with millions affected across the region.
The official death toll in Thailand currently sits at 170, with two deaths reported in Malaysia's northern Perlis state.
Elsewhere, there have been nearly 160 deaths in Sri Lanka due to a bout of particularly extreme weather that has caused flooding and mudslides.
An exceptionally rare tropical storm, named Cyclone Senyar, caused catastrophic landslides and flooding in Indonesia, with homes swept away and thousands of buildings submerged.
"The current was very fast, in a matter of seconds it reached the streets, entered the houses," a resident in Indonesia's Aceh Province, Arini Amalia, told the BBC.
She and her grandmother raced to a relative's house on higher terrain.
On returning the following day to retrieve some belongings, she said the flood had completely swallowed the house: "It's already sunk."
After waters rapidly rose in West Sumatra and submerged his home, Meri Osman said he was "swept away by the current" and clung onto a clothesline until he was rescued.
"During the flood, everything was gone," a resident of Bireuen in Sumatra's Aceh province told news agency Reuters.
"I wanted to save my clothes, but my house came down."
The bad weather has hampered rescue operations, and while tens of thousands of people have been evacuated, hundreds are still stranded, the Indonesian disaster agency said.
In Tapanuli, the worst-affected area, residents have reportedly ransacked shops in search of food.
Pressure is mounting on Jakarta to declare a national disaster in Sumatra to enable a faster and more co-ordinated response.
In Thailand's southern Songkhla province, water rose 3m (10ft) and at least 145 people died in one of the worst floods in a decade.
Across the 10 provinces hit by flooding, more than 3.8 million people have been affected, the government said on Saturday.
The city of Hat Yai experienced 335mm of rainfall in a single day last week - the heaviest in 300 years. As waters receded, officials recorded a sharp rise in the death toll.
At one hospital in Hat Yai, workers were forced to move bodies to refrigerated trucks after the morgue became overwhelmed, news agency AFP reported.
"We were stuck in the water for seven days and no agency came to help," Hat Yai resident Thanita Khiawhom told BBC Thai.
The government has promised relief measures, including compensation of up to two million baht ($62,000) for households that had lost family members.