At least 47 people have lost their lives in Nepal as torrential rains hit the region, the government said in a statement.
Twenty-nine people are reported missing amid floods and landslides, while 28 have been injured.
Heavy rains have also caused deaths in overcrowded Rohingya refugee camps in Bangladesh.
More than a million people have been affected by rising floodwaters as part of the seasonal monsoon.
Heavy rains are expected to continue in the coming days.
Police have rescued more than 1,100 people from across Nepal, affecting some 10,385 households.
A family of three was killed when part of their house collapsed in the capital, Kathmandu.
Bangladesh’s Cox’s Bazar – where more than a million Rohingya refugees are encamped after fleeing a military crackdown in Myanmar – has been hit by at least 58.5 centimetres of rain this month, according to the country’s meteorological department.
Hundreds of landslides since April have killed at least 10 people in the camps, including two Rohingya children in the last week.
The Brahmaputra River, which flows through India, Bangladesh and China, has burst its banks, swamping more than 1,800 villages in India’s north-east Assam state, Reuters reported.
“Ten people have died in separate incidents of drowning in the past three days and more than one million people (have been) affected, with the flood situation turning grave,” a state government flood bulletin said.
“The flood situation remains extremely critical,” Assam’s Water Resources Minister Keshab Mahanta said.
The monsoon season lasts from June to September and wreaks havoc across South Asia every year.
More than 1,200 people died in the region amid storms and landslides last year, while India’s Kerala faced its worst floods in almost a century.