From Reuters AlertNet, writer Biswajyoti Das gives us the details.
South Asia experiences monsoon rains from June to September, which are vital for its agriculture. But the rains frequently affect millions of people in countries like India, Bangladesh, Sri Lanka, Pakistan and Nepal - devastating crops, destroying homes and sparking outbreaks of diseases such as diarrhoea and dysentery.
Officials in India's northeast oil- and tea-rich state of Assam described the situation as "alarming". Two days of incessant rains have inundated hundreds of villages and forced residents to seek refuge on higher ground. Hundreds also remain stranded.
"Our priority now is to rescue marooned people. The situation is really bad and if the rain continues, people in affected areas will have a tough time," said a senior government official in Guwahati, Assam's main city.
The official, who declined to be named, said four people had died in Assam and around 200,000 had been displaced after more than 200 villages in the state's Lakhimpur and Dhemaji districts were submerged. Thousands of hectares of paddy crops are estimated to have been damaged.
Across the border in Nepal, officials said at least 73 people had been killed by landslides and floods, and another 25 were missing, since the start of the monsoon season last month. Around 750 people have been evacuated due to the threat of more landslides in Rukum district in the west of the Himalayan nation.
"Some of them are housed in tented camps and in schools while some people are staying with their relatives because of the danger to their houses from landslides," said home ministry official Bal Krishna Panthi.
Relief and rescue workers in Nepal said they were on alert and had started planting red flags along parts of the Kosi river to warn villagers of the potential flood threat.
The Kosi river in eastern Nepal remains a key concern for both India and Nepal after it broke its banks in 2008 and changed its course, submerging swathes of land and affecting more than two million people in the east Indian state of Bihar.