The majority of those killed were in the western state of Rajasthan, where 11 people died after lightning struck a watchtower near the 12th-century Amber Fort.
Senior police officer Anand Srivastava said some of those killed took selfies near the site on Sunday.
Srivastava added that at least nine others were killed and 20 injured in another round of airstrikes after the region was hit by monsoon rains and thunderstorms.
In neighboring Uttar Pradesh, 18 people lost their lives after being struck by lightning, according to a government official, most of whom were laborers working on farmland.
There are warnings from the country’s meteorological department that severe weather could continue for another two days.
Lightning is common during the Indian monsoon, which runs from June to September.
According to the most recent data available, more than 2,900 people were killed by lightning strikes in India in 2019.