Explained: Why is it so hot in India? Can we expect any respite?

New Delhi, Apr 29: The summer 2022 has set in. India is experiencing a blistering heatwave sweeping through vast swathes of the country.

Gurugram logged an all-time high of 45.6 degrees Celsius, breaking the previous record of 44.8 degrees Celsius on April 28, 1979. While Delhi saw the hottest April day in 12 years at 43.5 degrees Celsius.

According to weather experts, temperatures may even leap to 47 degrees Celsius in parts of northwest India.

What is a heat wave?

A heatwave is declared when the maximum temperature is over 40 degrees Celsius and at least 4.5 notches above normal. A severe heatwave is declared if the departure from normal temperature is more than 6.4 notches. Based on absolute recorded temperatures, a heatwave is declared when an area logs a maximum temperature of 45 degrees Celsius. A severe heatwave is declared if the maximum temperature crosses the 47-degree mark.

What are the heat wave prone states over India?

Heat wave generally occurs over plains of northwest India, Central, East & north Peninsular India during March to June. It covers Punjab, Haryana, Delhi, Uttar Pradesh, Bihar, Jharkhand, West Bengal, Odisha, Madhya Pradesh, Rajasthan, Gujarat, parts of Maharashtra & Karnataka, Andhra Pradesh and Telengana.

Sometimes it occurs over Tamil Nadu & Kerala also. Heat waves adversely affect human and animal lives.

Why is it so hot in India?

India has been recording higher than normal temperatures since the last week of March. Experts have attributed it to the absence of periodic light rainfall and thundershowers, typical for this time of the year, due to the lack of active western disturbances.

Accordingly, Northwest India saw at least four western disturbances in March and April, but they were not strong enough to cause a significant change in weather, Mahesh Palawat, Vice President (Meteorology and Climate Change), Skymet, a private weather forecasting agency told PTI.

The region did not see any significant pre-monsoon activity from March 1 to April 20 which compounded the severity of successive heatwave spells, he said, adding it had a ripple effect on central India, too.

Vidarbha in Maharashtra and west Rajasthan have consistently reported maximum temperatures in the range of 40 degrees Celsius to 45 degrees Celsius for the past two months.

India saw its warmest March since the IMD began keeping records 122 years ago amid a 71 percent rain deficit. Having recorded three prolonged heatwave spells, it could be one of the hottest April in the history of the country.

Can we expect respite from heat wave?

Heat wave spell is likely to continue till around May 1 or 2. Respite from heat wave conditions is likely next week. A fresh western disturbance is likely to affect northwest India from May 2 onwards.

According to a Indian Express report, thunderstorms and rainfall brought about by the active western disturbance and assisted by moisture-laden winds from the Bay of Bengal could bring some relief from soaring temperatures from May 2 to 5.

Few spells of rain, and strong winds could bring down the temperature to below 40 degrees.