THIRUVANANTHAPURAM: Kerala looks all set to experience the earliest onset of monsoon since 2009. Going by the India Meteorological Department (IMD), the southwest monsoon is likely to reach the state on May 27 this year — earlier than the usual date of June 1. Normally, southwest monsoon sets in over Kerala on June 1 with a standard deviation of about seven days.
According to IMD officials, the monsoon had arrived in the state on May 23 in 2009. In 2011, 2018 and 2022, it reached on May 29.
The arrival of the main rain-bearing system over the Indian mainland is marked by the onset of southwest monsoon over Kerala. It’s a significant indicator that shows transition from the hot season to the rainy season.
The IMD issues operational forecasts for monsoon onset using an indigenously developed statistical system with a model error of ± 4 days. The monsoon onset is predicted based on six factors — minimum temperatures over north-west India; pre-monsoon rainfall peak over south peninsula; mean sea level pressure over subtropical Pacific Ocean; outgoing long wave radiation over south China Sea; lower tropospheric zonal wind over northeast Indian Ocean and upper tropospheric zonal wind over Indonesia region. The Met department’s operational forecasts for monsoon since 2005 were correct except in 2015, said an official statement.
Meanwhile, IMD has issued hot and humid weather warning in the state for Sunday. Maximum temperatures are likely to be around 38 degrees Celsius at isolated places in Thrissur district and around 37 degrees Celsius in Kottayam, Kollam and Palakkad districts.