Intense early heat wave may not positively impact monsoon: meteorologists

IMD said last week that average maximum temperature this March across the country at 33.10 degree Celsius is highest ever in the past 122 years

Though it is sometimes commonly believed that intense summer heat has a positive impact on the initial thrust of southwest monsoon that follows immediately after, scientists and meteorologists say that there is no direct correlation between intense heatwave and monsoon, particularly when the wave is early into the season.

The India Meteorological Department (IMD) in an assessment released last week said that average maximum temperature recorded in March 2022 across the country at 33.10 degree Celsius is the highest ever in the last 122 years and it has broken the earlier highest ever of 33.09 Celsius recorded in March 2010.

“When heatwave is over the Central part of the country in the later stages of summer, that is in the months of May and June then it leads to increased activity of south-westerly winds blowing from the Pacific. Which in turn could have a positive impact on the initial burst of monsoon rains over Central India. But, if the wave is too early into the season like it has happened now, it might not have much of an impact,” Mahesh Palawat, Vice President Meteorology and Climate Change at private weather forecasting agency Skymet, told Business Standard.

Palawat said that apart, this year the La Nina is continuing and could move into an evolving stage around June which also means that Sea Surface Temperature in the coastal pacific region is still cool.

“Both these factors, heatwaves (only if the current pattern continues till May end or early June) and also expectations of neutral La Nina could have a positive impact on the southwest monsoon,” Palawat said.

However, the Director General of India Meteorology Department (IMD) Mrutunjay Mohapatra, discounted any positive correlation between the current spell of heatwave and the initial performance of the southwest monsoon.

Meanwhile, the IMD in its assessment of March also noted that over North-West India which comprises plains of Punjab, Haryana, Rajasthan and Delhi, in March 2022, the average maximum temperature was also the highest at 30.73 degree Celsius (earlier highest was in 2004 at 30.67 degree Celsius).

Over Central India in March 2022, the average maximum temperature was the second highest at 35.20 degree while over the southern Peninsular India, the average mean temperature was the fourth highest in March 2022 at 29.80 degree Celsius since 1901.