The deaths occurred Thursday and Friday in the coastal area of the state of Andhra Pradesh, where some 50,000 people sought refuge in relief camps on higher ground after their homes were flooded, disaster management official G.T. Priyadarshini said.
Tens of thousands of others have been affected by the flooding across India.
Reports from local officials in various parts of the country indicate at least 342 people have died so far in this year's monsoon, which runs from April to September. An accurate national death toll is not kept, and the total number of people killed across India is likely much higher.
"The situation is quite alarming but the administration in the affected districts is taking all the necessary measures to help the people," Priyadarshini said.
She said 26 deaths were reported from the Vizianagaram, Srikakulam and Vishakhapatanam districts of north coastal Andhra Pradesh, deluged under severe flooding for three days. Twenty-one others were injured in the three badly hit districts, and many of them were in serious condition.
The remaining deaths were from the East Godavari, Warangal and Adilabad districts. Officials said they feared there could be more casualties in areas where communication links had been cut off.
The weather office forecast more rains through Saturday.
The floods and heavy rains have paralyzed the state's road transport network, causing long pileups of vehicles on the highways and in cities. Most schools and offices were deserted.
The monsoon rains are eagerly awaited each year in India, where some 600 million people depend on agriculture for a living. However, they also bring widespread destruction, and thousands are affected annually in flooding.
Most of those killed either drown in floods, are crushed when poorly built houses collapsed or are electrocuted when raging waters expose live wires.