Police say people taking selfies near a watchtower at the 12th-century Amber Fort in the Indian city of Jaipur were among 11 who died after being struck by lightning.
Senior police officer Anand Srivastava said a further nine people were killed and nearly 20 others injured in separate lightning strikes as Rajasthan state was lashed with thunderstorms and monsoon rains.
In Uttar Pradesh, 18 people were killed by lightning on Sunday, said Manoj Dixit, a government official, bringing to 38 the death toll from both states. Most of those killed in Uttar Pradesh were farm workers in fields.
Both state governments announced financial compensation for the families of the victims and those who were injured.
The Indian meteorological department has warned of more lightning in the next two days.
Lightning strikes are common during India’s monsoon season, which runs from June to September. More than 2,900 people were killed by lightning in the country in 2019, according to the most recent official figures available.