The southwest monsoon is likely to reach Kerala on May 27, earlier than the usual date of June 1, the India Meteorological Department (IMD) said. If the monsoon arrives in Kerala as expected, it will be the earliest onset over the Indian mainland since 2009, when it began on May 23, according to IMD data. The arrival of the main rain-bearing system over the Indian mainland is officially declared when it reaches Kerala, usually around June 1.