Bhubaneswar, May 24: The southwest monsoon has made its onset over the Kerala coast, marking its earliest arrival over the Indian mainland since 2009.

Following its arrival, heavy rains are expected across the southern peninsula with Kerala, Tamil Nadu, and most parts of Karnataka, Andhra Pradesh, Rayalseema.

Normally, the southwest monsoon makes its onset over Kerala by June 1 and covers the entire country by July 8. It starts retreating from northwest India around September 17 and withdraws completely by October 15.

The monsoon had set in over the southern state on May 30 last year; June 8 in 2023; May 29 in 2022; June 3 in 2021; June 1 in 2020; June 8 in 2019; and May 29 in 2018, IMD data showed.

However, the monsoon arriving early or late in Kerala does not mean it will cover other parts of the country accordingly. It is characterised by large-scale variabilities and global, regional and local features, said an IMD official.

The southwest monsoon is extremely crucial for India’s agrarian economy, since it provides over 75 per cent of the annual rains over India in just four months from June to September. Once it sets in over Kerala, the monsoon takes over a month to cover the rest of the country and completes its journey by July 8, marking the beginning of the four-month season.