india

Updated: Mar 23, 2019 11:06 IST

After a winter that seemed it would never end, summer is here in Delhi with the India Meteorological Department (IMD) predicting that maximum temperatures will cross 35 degrees C over the next week. It could get hotter and touch 40 degrees by early April, the earliest it has done so in at least the past three years.

A two to three degrees Celsius rise in maximum temperature over the next three to four days will raise the maximum temperature to about 35 degrees and wrap up spring in March, said an IMD forecast.

Heat waves are also predicted in parts of northern and central India in April because of borderline El Nino conditions which may worsen the heat.

The term El Nino refers to large-scale ocean-atmosphere climate interaction linked to a warming in sea surface temperatures across the central and eastcentral Equatorial Pacific. “Currently, near-borderline El Nino conditions are prevailing over equatorial Pacific Ocean. The global forecasts indicate that near-borderline El Nino conditions are likely to persist during the March, April and May season and weaken thereafter,” said M Mohapatra, director general of meteorology at IMD.

“Some global studies suggest that the number of heat wave days is higher than normal in India during some El Nino years. If El Nino conditions are borderline this year, there may be a marginal impact on heat wave days. Heat waves also depend on many local and global factors like weakening or strengthening of westerlies, geology of the region...,” Mohapatra added.

The transition to summer seems quick this time mainly because of the frequency and intensity of western disturbances (storms originating in the Mediterranean region) that prolonged the feel of winter. There were more than 18 such this winter, well into March compared to the normal five or six.

“Though there was no sudden drop in temperature or cold wave conditions, the intensity of western disturbances this year prolonged the feel of winter. Now, the impact of western disturbances will weaken. The core heat wave zone will experience above-normal temperatures and heat wave conditions between March and May,” said Mohapatra.

“In fact, parts of Rayalseema and Tamil Nadu have already experienced temperatures above 40 degrees. Though we are not expecting heat waves in northern India in the next five days, it can happen after that,” Mohapatra added.

To be sure, temperatures are already higher in Delhi’s Palam (airport) weather station, like they usually are. In 2018, the temperatures here touched 40 degrees Celsius as early as March.

IMD in its seasonal outlook for March to May said that “normal to slightly above normal heat wave conditions are likely in the core heat wave zone during the season.” The core heat wave zone is Punjab, Himachal Pradesh, Uttarakhand, Delhi, Haryana, Rajasthan, Uttar Pradesh, Gujarat, Madhya Pradesh, Chhattisgarh, Bihar, Jharkhand, West Bengal, Odisha and Telangana and meteorological subdivisions of Marathawada, Vidarbha, Madhya Maharashtra and coastal Andhra Pradesh.

“The maximum temperature in the first week of April may be around 40 degrees. The maximum usually hovers around 40 degrees in April,” said Charan Singh, scientist at IMD.

The plains are said to be experiencing a heat wave when the maximum temperature is more than 45°C and a severe heat wave when the maximum temperature is more than 47°C. In the past week, the highest maximum temperature was 41.3 degrees at Anantapur in Rayalseema.

“It’s not unusual to experience temperatures close to 40 degrees or above 40 degrees early in April.” Last year, the maximum temperature rose to 40 degrees on April 17 and it remained above 40 degrees between April 14 and April 22 in 2017. The average normal maximum temperature in April however is 36.3 degrees,” added Singh.