Onset of monsoon over Kerala to be delayed, likely to be on June 4: IMD

The arrival of monsoon over the Kerala coast marks the beginning of the four-month monsoon season over the Indian sub-continent, which produces about 75 per cent of the country’s annual rainfall. Monsoon rain sustains large parts of India’s agriculture and is critical to the power sector as well. It is also crucial for maintaining sustainable flows in the rivers and dams.

The onset of monsoon over Kerala, however, is just a marker for the beginning of the season. It does not have any bearing on the quantity or quality of rainfall that happens during the season.

In the last five years, it stuck to the June 1 date only once (2020). In 2018 and 2022, it happened a couple of days earlier (May 29), while in 2019 and 2021, the onset happened a few days later. In three of these years, the country received more than 100 per cent rainfall. In 2018, when the onset happened on May 29, rainfall was deficient with the season producing only 90 per cent of the total normal rainfall.

The IMD has predicted normal rainfall (96 per cent) for this monsoon season. On an average, the country receives about 87 cm of rainfall during the four-month monsoon season.

However, since that forecast last month, there has been a change in situation with regard to the development of El Nino conditions in the equatorial Pacific region. El Nino, which refers to the unusual warming of the equatorial Pacific region, off the coast of Chile in South America, impacts weather events worldwide and, in particular, has the effect of suppressing rainfall over the Indian region. Recent forecasts suggest that El Nino was likely to develop much earlier than expected. So there is a threat of monsoon rainfall getting affected due to El Nino.

The IMD is expected to update its forecast for the monsoon later this month. This would include its assessment of the impact El Nino is likely to have on the seasonal rainfall. India has had normal monsoon rainfall for the last four years, thanks in part to an unusually long spell of La Nina, the opposite effect of El Nino, which aids rainfall over the Indian region.