The southwest monsoon hit Kerala on Tuesday, three days before its scheduled arrival, says the India Meteorological Department (IMD).
The onset of monsoon over the southern state marks the commencement of the four-month long rainy season in the country.
June 1 is the official onset date for arrival of monsoon in the country and it takes more than a month-and-half to cover the entire country.
The IMD has made a forecast of "normal" rainfall this season.
Skymet, a private weather forecasting agency and a rival of the IMD, had said that the monsoon made its arrival in Kerala on Monday.