Heavy monsoon rains caused at least 73 deaths in India's western state of Maharashtra, including at least 35 in a landslide, officials said.
Local journalists say dozens more people are trapped in mud and are unlikely to survive, putting the potential death toll at more than 100.
Parts of the west coast received up to 594mm of rainfall over 24 hours by Friday, forcing authorities to evacuate people from vulnerable areas as they released water from dams that were threatening to overflow.
"Unexpected very heavy rainfall triggered landslides in many places and flooded rivers," said Uddhav Thackeray, head of Maharashtra's state government.
"Dams and rivers are overflowing. We are forced to release water from dams, and, accordingly, we are moving people residing near the river banks to safer places."
The rains caused the worst floods in decades in the resort state of Goa, about 500 kilometres south of Maharashtra.
"People have lost virtually everything," said Goa's health minister Vishwajit Rane.
The state had not seen such heavy rains in half a century, he said, with more than 1,000 houses suffering serious damage.
Goa's chief minister Pramod Sawant said the monsoons had caused "widespread damage" but no casualties, unlike in neighbouring Maharashtra.
More than half of the deaths in Maharashtra were in Raigad district, where 35 bodies were recovered after a landslide struck a village on Friday. Another 15-20 people were feared trapped under the debris, the state's Relief and Rehabilitation Minister Vijay Wadettiwar said.
At least four people died in the state capital Mumbai after a building collapsed, and another 27 were killed in other parts of Maharashtra due to landslides and accidents linked to the heavy rainfall, state government officials said.
More than 1,000 people had to be rescued from the floods in Raigad, many of whom were stranded on rooftops and even on top of buses on highways, according to District Collector Nidhi Chaudhary.
Ms Chaudhary said the rains had eased and water levels started falling on Friday, but access to badly hit areas was still blocked, hampering rescue operations.
In neighbouring Ratnagiri district, another 200 people were rescued from hilly areas on Thursday after the heavy rains, the Press Trust of India news agency reported.
In the coastal town of Chiplun, home to 70,000 people, water levels rose to 3.5 metres in some areas following 24 hours of uninterrupted rain that caused the Vashishti river to overflow.
Rescue efforts were slowed by landslides in Raigad that blocked crucial roads including the Mumbai-Goa Highway.
Thousands of lorries were stuck on a national highway linking Mumbai with the southern technology hub of Bengaluru, with the road submerged in some places, a government official said.
India's meteorological department has issued red alerts for several regions in the state, indicating that heavy rainfall will continue for the next few days.
Last weekend, more than 30 people were killed in landslides caused by heavy monsoon rains in and around Mumbai, India's financial and entertainment capital.
Disasters caused by landslides and flooding are common in India during the June-September monsoon season, when heavy rains weaken the foundations of structures that are often poorly built.
The monsoon is crucial for crops planted during the season but the rains often cause extensive damage and kill scores of people each year.
Climate change is making India's monsoons stronger, according to a report from the Potsdam Institute for Climate Impact Research (PIK) published in April.
The report warned of potentially severe consequences for food, farming and the economy affecting nearly a fifth of the world's population.
"Since Indian society is overall affected by the monsoon in a very strong way, stronger variability produces problems for agriculture, but also for the organisation of public life," said Anders Levermann from PIK and Columbia University.