Days of torrential downpours have washed away vehicles, demolished buildings and destroyed bridges in the Himalayas.
Flooding and landslides are common and cause widespread devastation during India's treacherous monsoon season, but experts say climate change is increasing their frequency and severity.
At least 52 people have been killed in Himachal Pradesh since Sunday, with thousands more stranded after disruptions to roads, power lines and communication networks.
"The suffering of those affected cannot be relieved with money, but the government will provide all possible help to them in this hour of distress," state chief minister Sukhvinder Singh Sukhu said in a statement on Tuesday.
Sukhu said earlier that up to 20 others were feared trapped under rubble after landslides, and appealed to residents to stay indoors and avoid going near rivers.
Images from hard-hit areas in Himachal Pradesh showed bodies being pulled from piles of dark earth that had crushed buildings and smashed roofs.
At least 11 people died when a landslide triggered the collapse of a popular temple for the Hindu deity Shiva in state capital Shimla.
"The rescue work is ongoing and we fear that at least 10 more people are still trapped under the rubble," district disaster management committee chair Aditya Negi told AFP.
Elsewhere in the state, railway lines were seen dangling in midair after the ground beneath them was washed away.
Sukhu said the disaster was the worst to hit Himachal Pradesh in the past 50 years, adding that state authorities had scaled down Tuesday's annual celebrations of Independence Day, marking the end of British colonial rule, to concentrate on rescue efforts.
More than 300 tourists had been rescued from the floods, he added.
Prime Minister Narendra Modi, speaking from the Red Fort in New Delhi for his annual Independence Day address, said that recent natural disasters had caused "unimaginable troubles" for families across the country.
"I express my sympathies towards all of them and I assure them that state and central governments will work together," he told the crowd.
Yoga retreat
At least 13 more people have also been killed since Friday in neighboring Uttarakhand state, officials said Tuesday.
Rescue teams there raced to remove debris after people were feared buried when heavy rainfall triggered landslides.
Five people were buried when a landslide hit a resort near the popular yoga retreat of Rishikesh on the banks of the river Ganges.
Nearly 350 roads around Uttarakhand had been closed to traffic, according to state disaster bulletins.
Several riverside towns and villages in both states were at risk of flash floods from the heavy rain forecast.
The monsoon brings South Asia around 80 percent of its annual rainfall and is vital for both agriculture and the livelihoods of millions. But it also brings destruction every year in the form of landslides and floods.
Days of relentless monsoon rains killed at least 90 people last month, while the capital New Delhi saw the Yamuna River -- which snakes past the megacity -- record its highest levels since 1978.
Forecasters expect heavy rains to continue across the Indian Himalayas until at least Friday.