Heatwave in the east in May, northwest to be cooler: IMD

The national weather agency has begun to issue 'heat index' for different parts of the country on an experimental basis

After a scorching April, eastern India once again is likely to experience heatwaves in May, India Meteorological Department warned on Friday, noting that the northwest will be relatively cooler.

“Above-normal heat wave days are expected over most parts of Bihar, Jharkhand, Odisha, Gangetic West Bengal, east Uttar Pradesh, coastal Andhra Pradesh and some parts of north Chhattisgarh, east Madhya Pradesh, Telangana and coastal Gujarat in May,” IMD director general Mrutyunjay Mohapatra said here.

In contrast, there will be less probability of heatwaves in the northwestern states like Punjab, Haryana, Delhi and part of Rajasthan where the monthly average of maximum temperature would be normal to below-normal. The same is true for west-central India.

The alert for May is once again a concern for east India where many stations reported temperatures higher than normal by 4.5 degrees Celsius over east and northeast India as indicated in the heatwave outlook issued by the IMD for April 2023.

Read | Mercury soars across India; Hamirpur, Prayagraj in UP hottest at 44.2 degrees Celsius

The national weather agency has begun to issue a “heat index” for different parts of the country on an experimental basis, taking into account air temperature and relative humidity. The index will give people 'a sense of what the temperature actually feels like,' in addition to the day’s maximum and minimum temperatures.

The problem, however, is that the index has not been validated for India. The IMD relies on a formula provided by the USA's National Oceanic and Atmospheric Administration to calculate the heat index and uses the comfort levels of weather experienced by Americans in their regions.

“We have to work with the Union Health Ministry to validate the observations for Indian cities. For example, in India, 40 degrees Celsius temperature and 20 per cent relative humidity could be okay, but the same is intolerable for a person residing in the US,” said M Ravichandran, Secretary, Ministry of Earth Sciences.

On the monsoon front, Mohapatra said the dreaded El Nino conditions would develop during the second half of the monsoon season, but the indications so far pointed towards a moderate one. India receives a poor monsoon in 60 per cent of the El Nino year.

Earlier this month, IMD forecasted that despite the El Nino threat India would have a normal monsoon this year with the country receiving 96 per cent of its average seasonal rainfall between June and September.