What Causes An Early Monsoon And What Does It Mean For Indian Heatwave?

The south-west monsoon has been predicted to be early this year as it’s expected to reach Andaman and Nicobar islands on May 15 – a full week ahead of schedule. 

The Indian Meteorological Department also predicted that Kerala will witness monsoon onset on May 27, five days earlier than the normal onset date. It’s expected to be the earliest monsoon in Kerala since 2009.

The monsoon is extremely important for India. Its onset marks the four-month long rainy season in India which brings around 70 per cent of the country’s rainfall. It’s considered to be the lifeline of India’s agricultural economy.

Here is all you need to know about the early onset of monsoon and what it means for the ongoing heatwave. 

What causes an early monsoon?

Weather experts attribute the early onset of southwest monsoon over Kerala to the influence of the remnants of Cyclone Asani that triggered the cross-equatorial flow, a key factor for the seasonal rains.

Last year too, a cyclone – named Yaas – had caused the timely arrival of monsoon in Andaman and Nicobar islands. 

This year, Cyclone Asani dragged moisture towards Andaman and Nicobar islands a week ahead of the normal progress of the monsoon winds, as per a report.

What does it mean for heatwave?

The early arrival of the south-west monsoon comes at a time when parts of Northwest India were experiencing extremely high maximum temperatures. Cycline Asani gave a temporary relief from the heat.

Winds from Cyclone Asani had given relief to Delhi from the heatwave in recent days but the weather department has issued a heatwave warning again. 

IMD has issued an “orange alert” for Friday, warning that the temperature may soar to 46-47*C in parts of the city, whereas a “yellow alert” has been sounded for Sunday.

However, cloudy skies and thunder may provide some relief from the intense heat next week.

It would take three to four weeks for the monsoon to spread to other parts of the country after hitting Andaman and Nicobar islands in its first stop. Further relief from the heat is expected then. 

Does early monsoon mean more rain?

Early or late arrival of monsoon does not mean it would bring lesser or more rainfall. 

A report in The Indian Express noted, “In a recent year, the onset of the monsoon occurred two days in advance of the normal date, and it rained heavily for about 10 days after that — however, the season as a whole ended with 14% less rain than normal.”

Earlier this year, IMD predicted a “normal” monsoon. It means the rainfall is likely to be in the range of 96-104 per cent of the long period average of the years 1971-2020, according to the Express report. The average annual monsoon rainfall in this period was 87 cms.