Weeks of sweltering temperatures have caused more than 160 deaths in southern and eastern India, officials said, warning that any relief from monsoon rains was still probably weeks away.
Most of the heatwave victims were labourers and farmers in the states of Telangana, Andhra Pradesh and Orissa, though temperatures elsewhere in India have also hit 45C.
Schools were closed last week in Orissa until at least April 26.
Officials in Andhra Pradesh were giving out free water and buttermilk to help people stay hydrated.
And everywhere, people have been urged to stay indoors during the hottest hours of the day.
The temperatures were about 4-5C (8-10F) hotter than normal for April, state meteorological official YK Reddy said.
"Normally such high temperatures are recorded in the month of May," he said.
Police have reported 55 heat-related deaths in Orissa and at least 45 in Andhra Pradesh.
Sixty-six were reported in Telangana, though the state's deputy chief minister, Mohammed Mahmood Ali, said the causes of death were still being verified.
A 12-year-old girl in the drought-stricken western state of Maharashtra died from the heat while fetching water, Indian broadcaster NDTV said.
India is grappling with severe water shortages and drought affecting more than 300 million people - a quarter of the country's population.
Thousands of distressed farmers have committed suicide, tens of thousands of farm animals have died and crops have perished, with rivers, lakes and ponds drying up and groundwater tables sinking.
Scrambling to deal with the crisis, officials have sent tankers of water to parched farming communities in Maharashtra, banning people from drilling deep wells and ordering farmers to shift away from growing water-guzzling sugarcane crops.
The heatwave in India coincides with record-high temperatures across the globe.
March's average global temperature of 12.7C (54.9F) was not only the hottest March, but continues a record 11-month streak that started last May, the US National Oceanic and Atmospheric Administration said.
For southern India, this is the second consecutive year marred by a deadly heatwave. Last year, around 2,500 people died in scorching temperatures before the monsoon rains began in the Indian subcontinent in early June.
But while heatwaves are relatively common during Indian summers, authorities have done little to ensure water security or prepare urban populations for the risks.
This year Orissa's capital, Bhubaneshwar, and Maharashtra's city of Nagpur joined Gujarat's Ahmedabad in launching a heatwave programme to educate people on how to stay cool, provide shelters and train medical workers on dealing with heat-related illnesses such as sunstroke and dehydration.