The southwest monsoon set in over Kerala on Friday, the Met office said.
Heavy rains have lashed most parts of the state since Thursday night. Thiruvananthapuram received rains on Friday morning.
"The southwest monsoon has set in over Kerala on June 5, as against the normal date of June 1," an India Meteorological Department statement said.
"Conditions are favourable for the further advance of southwest monsoon into some more parts of central Arabian Sea, Karnataka, Tamil Nadu, some parts of Rayalseema and coastal Andhra Pradesh, some parts of central and north Bay of Bengal and southern parts of northeastern states during the next 48 hours."