Temperatures have risen above 40C in at least seven states, which is highly unusual, and local media reports say that more than 100 people have died of sun stroke.

The BBC’s correspondents in affected areas describe the situation in their respective localities:

Rahul Tandon in Kolkata (Calcutta)

Kolkata is a city where people like warmth. During the “winter” month, when temperatures dip to 15C or so, the city streets are full of people wearing woollen “monkey caps” and thick ear muffs.

But even here people are fed up with the heat - every morning they wake up and pray to various gods and goddesses for rain.

But there is not a cloud in the sky and it’s getting hotter and hotter with temperatures soaring above 40C every day.

Manish Nag, who has lived in this city for more than 60 years, has not left home for the past week.

Sitting under a slowly whirring fan in his flat, he says that he has never experienced such heat and is scared that he will fall ill if he ventures out.

He may have to stay indoors for a while, as there is no sign of rain.

Government schools are shut, the streets are full of brightly coloured umbrellas, coconut water sellers are cashing in and people, desperately searching for some shade, are crowding under trees.

It is election time here and politicians are promising voters everything under the sun. But they cannot stop it from shining.

Imran Qureshi in Bangalore

In south India, temperatures are at least two to three degrees above normal.

It feels more like the end of May rather than middle of April. This is mainly due to the absence of April showers that the region is accustomed to.

Summer vacations in schools in Telangana have been extended by a week, while government offices will open at 8.30am and shut at 1pm.

According to local Meteorological department officials, a heatwave still cannot be declared in the regions of Andhra Pradesh, Telangana and north Karnataka until temperatures rise at least another 5C.

But dozens of people are believed to have died in the region and disaster management departments are worried about a severe shortage of water.

”If it doesn’t rain in the coming week, it will certainly lead to a heatwave. We are closely monitoring the situation,” a Karnataka government official told the BBC.

Alok Putul in Raipur

In the central Indian state of Chhattisgarh, summer arrived very early.

Bilaspur town recorded a temperature of 40C in just the second week of March.

The rise and fall in temperature has been constant in the state, but elderly people who live in towns like Bilaspur and Durg insist that they have never seen such harsh summers before.

On Thursday, the temperature in Bhilai reached 44C. It was the same in many towns in the state on Friday.

Weather experts say the temperatures are likely to remain the same in the near future.

S Niazi in Bhopal

The summer is well and truly underway in the central Indian state of Madhya Pradesh.

The temperature in the state capital, Bhopal, has crossed 40C while in the cities of Khajuraho and Khargon, it’s even higher at 42C.

Many other districts in the state are also witnessing high temperatures.

According to the Meteorological department, there will be no respite from the heat in the next fortnight.

As a precautionary measure, the state authorities have ordered schools to shut at 1pm.

Niraj Sinha in Ranchi

Jamshedpur is the hottest city in the central Indian state of Jharkhand with temperatures rising to 42.6C on Thursday.

Many other towns, including Ranchi, Chaibasa, Dhanbad and Palamau, are also in the grip of a heatwave, recording temperatures between 40C and 42C.

Many parts of the state are facing water scarcity as well.

Authorities have ordered all government schools to shut at 11:30am while even private schools in Ranchi are not holding classes beyond 12:30pm.

The education department has asked officials to ensure water supply in all schools and hold health camps on Saturdays.

A senior Met department official in Ranchi, Upendra Srivastava, told BBC Hindi that the temperature now is running three to four degree Celsius above normal and is likely to rise further.