Intense heat swept large swathes of India on Sunday, with maximum temperatures settling four to six degrees Celsius above normal in many areas.

According to the India Meteorological Department (IMD), maximum temperatures hovered between 42 and 45 degrees Celsius in parts of Odisha and Rayalaseema, Gangetic West Bengal, Jharkhand, Vidarbha, Chhattisgarh, Madhya Pradesh, Telangana and Andhra Pradesh.

Parts of Bihar, Madhya Pradesh, Tamil Nadu, Puducherry and Uttar Pradesh recorded maximum temperatures between 40 and 42 degrees Celsius.

Maximum temperatures settled 4 to 6 degrees Celsius above normal in many parts of Gangetic West Bengal, Bihar, Jharkhand and Odisha; and 2 to 4 degrees above normal in parts of sub-Himalayan West Bengal, Sikkim, Andhra Pradesh, Tamil Nadu, Puducherry & Karaikal, Chhattisgarh, Madhya Pradesh, Vidarbha and Telangana, the IMD said.

The ongoing heat wave is the second heatwave spell this month. The first spell scorched parts of Odisha, Jharkhand, Gangetic West Bengal, Telangana, Andhra Pradesh, Tamil Nadu and Gujarat.

On Sunday, Bahargora in Jharkhand recorded a maximum temperature of 46 degrees Celsius, Baripada in Odisha 44.6 degrees, and Bankura in West Bengal 44.5 degrees.

Bulandshahr in Uttar Pradesh registered a high of 44 degrees Celsius and Washim in Vidarbha 43.6 degrees.

The threshold for a heat wave is met when the maximum temperature of a weather station reaches at least 40 degrees Celsius in the plains, 37 degrees in the coastal areas and 30 degrees in the hilly regions, and the departure from normal is at least 4.5 notches. A severe heat wave is declared if the departure from normal temperature exceeds 6.4 notches.

Amid the prevailing but weakening El Nino conditions, the IMD had earlier warned of extreme heat during the April-June period when around a billion people are expected to exercise their franchise during the seven-phase Lok Sabha elections, heightening concerns about vulnerability to heat waves.

Voting for the first phase of elections took place on April 19.

The Met office has said four to eight heatwave days are expected in different parts of the country in April against a normal of one to three days. Ten to 20 days of heatwave days are expected against a normal of four to eight in the entire April-June period.

The areas and regions predicted to witness a higher number of heatwave days are Madhya Pradesh, Gujarat, Odisha, Andhra Pradesh, madhya Maharashtra, Vidarbha, Marathwada, Bihar and Jharkhand. Some places may record more than 20 heatwave days.

The intense heat could strain power grids and result in water shortages in parts of India.

Global weather agencies, including the IMD, are also expecting La Nina conditions to develop later in the year.

El Nino conditions -- periodic warming of surface waters in the central Pacific Ocean -- are associated with weaker monsoon winds and drier conditions in India. La Nina conditions -- the antithesis of El Nino -- lead to plentiful rainfall during the monsoon season.

In a mid-April update, the IMD said India would experience above-normal cumulative rainfall in the 2024 monsoon season with La Nina conditions, expected to set in by August-September, being the dominant factor.

The monsoon is critical for India's agricultural landscape, with 52 per cent of the net cultivated area dependent on it. It is also crucial for replenishing reservoirs critical for drinking water apart from power generation across the country.

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