Officials in the Indian city of Calcutta say the city has received around 20% of the monsoon rain it normally gets over the last three days.
At least 16 people in the city have died in floods caused by the rain.
Storms have affected large parts of South Asia, with at least 140 people killed this week elsewhere in India.
The international Red Cross has launched an emergency appeal to help hundreds of thousands of flood victims in Pakistan and Bangladesh.
It says that it wants to raise $9m to assist 98,000 people left in dire conditions in flood-stricken areas of Pakistan, and $685,000 dollars for relief efforts to help 133,000 in Bangladesh who require food, clothing, health care and shelter for the next six months.
The International Federation of Red Cross and Red Crescent Societies (IFRC) says that large parts of the province of Balochistan remain submerged following the impact of Cyclone Yemyin last Tuesday coupled with heavy monsoon rains over the weekend.
"When you walk through areas of Baluchistan, the air smells of rotting goat carcasses and the heat is so stifling that many people are covering themselves in mud just to keep cool," Asar ul Haq, the IFRC's head of disaster management in Pakistan said in a statement.
"We're expecting more rain in the coming days, which will heighten the risk of malaria, while we're also seeing new cases of diarrhoea," he said.
More rain predicted
The Calcutta weather office said the city has received more than 300mm of rain since late on Monday night.
"Calcutta gets between 1600 to 1700mm of rain every monsoon and now he have got so much rain in just three days," G Debnath, chief of the local weather office said.
Few taxis and buses could be seen on roads. The hand-pulled rickshaws are ferrying stranded residents.
Schools and colleges have been shut due to the heavy rains. Attendance in offices was low, officials said.
The weather office predicts more rain until Friday.
Officials say the army has been deployed in boats to help hundreds of thousands of people marooned because of the flooding.
Transport infrastructure has been hit in Gujarat
The authorities fear more flooding, and have used loudspeakers to ask residents to keep adequate food stocks at home, or leave their residences for dry land. Many grocery shops were closed.
Hospitals and universities have been flooded, while train services were disrupted.
The city's IT hub, which has the offices of many multi-national companies, was also hit.
In Gujarat at least 80 people died. Transport infrastructure throughout the state has been badly hit.
Highways have disappeared under flood waters and many dams have been overflowing with some touching the danger mark.
Many factories were forced to close in the highly industrialised state.