The onset of monsoon over Kerala will be delayed by four days, the India Meteorological Department said on Tuesday. It is expected to happen on June 4 this year, it said. The normal date for the onset of monsoon over the Kerala coast is June 1. It marks the beginning of the four-month monsoon season, which brings about 75 per cent of India’s annual rainfall. In the last five years, only once has the onset happened on June 1. On two occasions, in 2018 and 2022, it happened a couple of days earlier, on May 29, while in 2019 and 2021, the onset happened a few days later. The onset of monsoon is just a marker for the beginning of the rainfall season. It has no bearing on the amount of rainfall that happens during the season.
“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 IMD said in a statement. The six predictors of monsoon onset used in the models are: i) Minimum Temperatures over Northwest India ii) Pre-monsoon rainfall peak over south Peninsula iii) Outgoing Long wave Radiation (OLR) over south China Sea (iv) Lower tropospheric zonal wind over Southeast Indian Ocean (v) Mean sea level pressure over Subtropical NW Pacific Ocean (vi) Upper tropospheric zonal wind over North East Indian Ocean. 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.Meanwhile, the Met department said that duststorms and dust-raising winds are very likely in isolated pockets over Haryana and Delhi, West Uttar Pradesh and Rajasthan during the next three days and over Madhya Pradesh and Vidarbha region during the next two days.