New Delhi: The India Meteorological Department (IMD) announced the arrival of the monsoon in Kerala on May 24, 2025, a week ahead of its usual June 1 onset. This marks the earliest monsoon onset over the Indian mainland since May 23, 2009, driven by a depression over the Arabian Sea.
Depression Fuels Early Monsoon
A low-pressure area off the south Konkan coast intensified into a depression, centered over the east-central Arabian Sea. The IMD reported that this system, expected to cross the coast between Ratnagiri and Dapoli by Saturday forenoon, has triggered increased rainfall in Kerala. The IMD’s criteria for declaring monsoon onset—consistent rainfall of 2.5 mm or more across 60% of 14 designated stations, south-westerly winds, and low Outgoing Longwave Radiation—were met, confirming the early arrival.
Factors Behind the Early Onset
The IMD noted that the absence of a ‘heat low’ over Northwest India, which typically pulls moist air from the monsoon trough, has not hindered this year’s early onset. A May 20, 2025, report highlighted that a normal monsoon depends on such atmospheric patterns, yet favorable conditions like the Arabian Sea depression have accelerated the process. IMD data indicates that early onsets, as seen in 2009, often correlate with robust monsoon seasons, though total rainfall predictions remain under review.