Governments and aid groups in Indonesia and Sri Lanka worked on Tuesday to rush aid to hundreds of thousands stranded by deadly flooding that has killed 1,300 people in four countries.

Torrential monsoon season deluges paired with two separate tropical cyclones last week dumped heavy rain across Sri Lanka and parts of Indonesia's Sumatra, southern Thailand and northern Malaysia.

Climate change is producing more intense rain events because a warmer atmosphere holds more moisture, and warmer oceans can turbocharge storms.

AFP analysis of US weather data showed several flood-hit regions across Asia experienced their highest November rainfall totals since 2012.

The floodwaters have now largely receded, but the devastation means hundreds of thousands of people are living in shelters and struggling to secure clean water and food.

In Indonesia's Aceh, one of the worst-affected regions, people told AFP that anyone who could afford to was stockpiling.

"Road access is mostly cut off in flood-affected areas," 29-year-old Erna Mardhiah said as she joined a long queue at a petrol station in Banda Aceh.

"People are worried about running out of fuel," she added from the line she had been waiting in for two hours.

The pressure has affected prices.

"Most things are already sky-high... chillies alone are up to 300,000 rupiah per kilo (US$18), so that's probably why people are panic-buying," she said.

On Monday, Indonesia's government said it was sending 34,000 tons of rice and 6.8 million litres of cooking oil to the three worst-affected provinces: Aceh, North Sumatra and West Sumatra.

"There can be no delays," Agriculture Minister Andi Amran Sulaiman said.

But Alfian, a resident in Banda Aceh, told AFP the government had been "very slow, especially in ensuring basic necessities".

Even areas that were not directly affected were seeing shortages because of blocked transport links.

In Dolok Sanggul in North Sumatra, one resident told AFP he had been lining up since Monday afternoon for fuel, and spent the night sleeping in his car.

"When we were about to enter the gas station, the fuel ran out," he said.

Aid groups warned that local markets were running out of essential supplies and prices had tripled.

"Communities across Aceh are at severe risk of food shortages and hunger if supply lines are not reestablished in the next seven days," charity group Islamic Relief said.

The weather system that inundated Indonesia also brought heavy rain to southern Thailand, where at least 176 people were killed.

Across the border in Malaysia, two more people were killed.

A separate storm brought heavy rains across all of Sri Lanka, triggering flash floods and deadly landslides that killed at least 410 people.

Another 336 remain missing, and an official in the central town of Welimada told local reporters he expected the toll to rise, as his staff dug through the mud looking for victims buried by landslides.

President Anura Kumara Dissanayake has declared a state of emergency to deal with what he called the "most challenging natural disaster in our history". (AFP)