At least 160 people are reported to have been killed in floods and landslides following days of torrential rain in Nepal and northern India.
In Nepal, officials said at least 101 people were known to have died after rescuers found four more bodies. More than 130 people are still missing.
In northern Indian states severe flooding after rainfall left at least 60 dead and entire villages marooned.
The worst of the rain is now thought to be over.
Landslides and flooding devastated rural communities and cut off roads throughout the region. In Nepal, officials voiced fears about a possible cholera outbreak.
Rescue helicopters have been deployed to convey emergency supplies to those stranded.
More than 1,500 villages are inundated in India's Uttar Pradesh state where 28 people have died and thousands have been left homeless.
In Uttarakhand, cloudbursts and landslides killed 32 and in Bihar at least two people have died.
"The flood situation arose following heavy downpours in Nepal, which led to overflowing rivers which originate in the Himalayan region including Tibet and Nepal," news agency Reuters quoted chief secretary of Uttar Pradesh Alok Ranjan as saying.
In the north-eastern Assam state, the water level has risen to alarming levels in the Brahmaputra and its tributaries, flooding large areas and killing one person, reports the Press Trust of India.
The Kaziranga National Park and the Pobitora Wildlife Sanctuary are also heavily flooded, forcing animals to move to highlands to protect themselves, the agency added.