Southwest Monsoon likely to set over Kerala on May 27: IMD

This year, the southwest monsoon is likely to set over Kerala to be on 27th May, informed the India Meteorological Department (IMD) on Saturday. The arrival of the southwest monsoon over the Indian subcontinent officially begins with its onset in Kerala, signaling a critical climatic shift.

This transition marks the end of the intense summer heat and ushers in the much-anticipated rainy season, bringing a wave of relief to parched regions. Kerala serves as the traditional gateway for the southwest monsoon, and its timely arrival is closely monitored by meteorologists and agriculturists alike. Historically, the monsoon reaches the Kerala coast around June 1, though this date can vary by about a week on either side.

As the monsoon advances northward, it progressively cools the northern and central parts of India, alleviating the harsh effects of the preceding dry months. The onset in Kerala thus not only symbolizes the beginning of seasonal rainfall but also plays a crucial role in shaping India's agriculture and water resource planning for the year.

IMD’s operational forecasts of the date of monsoon onset over Kerala during the past 20 years (2005-2024) were proved to be correct except in 2015. 

IMD Forecast Method

India Meteorological Department (IMD) has been issuing operational forecasts for the date of monsoon onset over Kerala from 2005 onwards. An indigenously developed state-of-the-art statistical model with a model error of ± 4 days is used for the purpose. 

The 6 Predictors used in the models are: 

Minimum Temperatures over North-west India

Pre-monsoon rainfall peak over south Peninsula

Mean sea level pressure over Subtropical NW Pacific Ocean

Outgoing Long wave Radiation (OLR) over south China Sea

Lower tropospheric zonal wind over Northeast Indian Ocean

Upper tropospheric zonal wind over Indonesia Region