Mixed weather in store for India next month, says IMD

The peak summer month of May is likely to record normal or below normal temperatures in northwest and west-central India, the India Meteorological Department (IMD) said in its monthly outlook on Friday, in what could bring respite to millions of people living in some heatwave-prone states, although other parts --- where extreme highs are not as common – may record hotter-than-usual temperatures.

Rain, too, is expected to be normal or above normal in the northwest and west-central regions, but conditions are likely to be less pleasant in east, east-central, northeast India and peninsular India, where there may be higher than usual number of heatwave days.

“Normally in May, maximum temperatures are above 40°C but this time they are expected to be mostly lower than this threshold and in the below-normal category over northwest India and west-central India. The region is also unlikely to record heat waves but isolated heat wave events may occur,” said M Mohapatra, director general, IMD.

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In a separate presentation on warming trends over Indian states, IMD revealed Himachal Pradesh is recording a warming trend of 1.5°C since 1901.

Among the places where above-normal heatwave is expected in May are Bihar, Jharkhand, Odisha, Gangetic West Bengal, east Uttar Pradesh, coastal Andhra Pradesh, some parts of north Chhattisgarh, east Madhya Pradesh, Telangana and coastal Gujarat.

Average nationwide rainfall in May is likely to be normal (91- 109% of the long-period average) with northwest, many parts of west-central India and northern parts of peninsular India likely to record higher-than-normal rain. Below normal precipitation is likely in most parts of northeast India, many parts of east-central India and the southern peninsula, the weather department said in its forecast.

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On the contrary, east and east-central India, which normally doesn’t experience frequent heatwaves, are likely to record several hot spells. “(Typically) due to proximity to Bay of Bengal (BoB) and the moisture from it, there is frequent thunderstorm activity over the eastern region during this season, which keeps temperatures under check. But our models indicate that moisture incursion may be low during May due to a weak anticyclone over BoB,” explained Mohapatra.

The model projects could “also mean that Western Disturbances that impact northwest India during this period will not have any impact on east India,” Mohapatra added.

Northwest India is expected to record more thunderstorm activity and rainfall under the influence of western disturbances, officials said, in keeping with the trend being recorded at present, when the latter half of April is turning out to be cooler than usual.

But the latter half of the summer and the following monsoon season is likely to be warmer than usual due to the El Nino phenomenon. The IMD’s new assessments on Friday showed El Nino conditions will develop by June, with a 72% probability of it happening during May, June and July, period and an over 80% probability of it developing during June, July and August period.

El Nino is characterised by an unusual warming of waters in the eastern equatorial Pacific, which has a high correlation with warmer summers and weaker monsoon rains in India.

IMD’s extended range forecast indicates considerably below normal temperatures over most parts of the country till around May 11.

Himachal Pradesh breaches 1.5°C warming threshold

Separately, IMD said an analysis of its long-term data from 1901 to 2022 showed all states were recording considerable warming, but Himachal Pradesh has the highest increase in mean temperature, having already warmed by 1.5°C since 1901.

It is followed by Goa, which has a warming trend of 1.44°C for every 100 years, and Kerala 1.05 °C for every 100 years.

“The temperature rise trend is far higher in the north than the south. In fact, in polar regions, you will find there is warming up to 3°C so the rate of increase is higher in high latitude regions. The same is true for the Himalayan region,” Mohapatra said.