IMD: Slight delay in monsoon onset over Kerala; likely to be on June 4

The onset of monsoon over Kerala will likely be around June 4, the Indian Meteorological Department (IMD) said on Tuesday, highlighting a slight delay. The southwest monsoon normally sets in over Kerala on June 1 with a standard deviation of about seven days.

Last year, the onset of monsoon over Kerala occurred on May 29, two days after IMD’s predicted date. The operational forecasts of the date of monsoon onset over Kerala during the past 18 years (2005-2022) were proved to be correct except in 2015, the IMD said.

The IMD said in a statement,“ This year, the southwest monsoon onset over Kerala is likely be slightly delayed than normal date of onset. The monsoon onset over Kerala is likely to be on 4th June with a model error of ± 4 days.”

The advance of the southwest monsoon over the Indian mainland is marked by the onset over Kerala and is an important indicator characterizing the transition from the hot and dry season to the rainy season.

The six predictors of monsoon onset used in the models are Minimum Temperatures over Northwest India, Pre-monsoon rainfall peak over south Peninsula, Outgoing Long wave Radiation (OLR) over south China Sea, Lower tropospheric zonal wind over Southeast Indian Ocean, Mean sea level pressure over Subtropical NW Pacific Ocean and Upper tropospheric zonal wind over North East Indian Ocean.

The IMD had last month said India is expected to get normal rainfall during the southwest monsoon season despite the evolving El Nino conditions.