Authorities said most of the victims were construction workers, the elderly or the homeless. In the national capital, the torrid temperatures melted roads and forced people indoors.
Heat waves, periods with unusually high temperatures, typically occur between March and June.
Authorities advised people to stay indoors and consume plenty of fluids as experts warned the heat wave is expected to continue till the weekend.
There were also fears of large-scale power outages in several parts of north India, bringing back memories of a major blackout in 2012 that affected nearly 600 million people.