A red alert indicates heavy to extremely heavy rains of over 20 cm in 24 hours, while orange alert means very heavy rains from 6 cm to 20 cm of rainfall. A yellow alert means heavy rainfall between 6 to 11 cm.
The IMD said squally weather with wind speed reaching 40-50 kmph is likely to prevail over Kerala coast and advised fishermen not to venture into the sea till May 16.
The weatherman has also issued a yellow alert for Malappuram, Kozhikode and Wayanad districts on these days.
Since it was raining in the southern part of the state for the past few days, the district administrations have issued a warning to people staying in low lying areas, on the banks of the rivers and hilly regions to remain vigilant.
The IMD has previously predicted that the Southwest monsoon, which is also known as Edavapathi in the state, is likely to bring the first showers to Kerala by May 27, five days earlier than the normal onset date.