From today, Christian Aid's response will include distributing emergency food rations, water and cooking utensils to stranded people in the Indian state of Bihar, one of the worst hit.
'This level of constant rainfall in Bihar and Uttar Pradesh states is unprecedented. We have never witnessed this before,' said Anand Kumar, from the Christian Aid office in India.
'The monsoon season usually starts in late August. But this year we have already had 15 days of sustained rainfall.'
Experts are already associating the levels of flooding with the effects of climate change. Given the current predictions for global warming, such disasters and floods are set to become worse and more frequent in the future.
The south Asia floods demonstrate just how vulnerable the poorest communities are to the effects of climate change. Christian Aid has worked in Bihar state for many years, as it is home to some of the most marginalised people in India.
Christian Aid partner organisations are already beginning the distribution process for emergency food rations, cooking utensils, water purification tablets and clothing for people marooned by the floods in both Bihar and Uttar Pradesh. Delivery will begin today, initially targeted to reach 50,000 people.
In India, many of the most vulnerable are lower caste farm labourers and their families, known as Dalits. They have not only lost their homes, but are also losing the chance of vital income.
In Bangladesh, food rations will initially be distributed to 35,000 people in low-lying areas that were the worst hit by the flooding.
The rainy season is only just beginning and the floods could yet worsen. But even when the water levels subside, communities will need help for months in order to rebuild their lives.