Cyclonic Storm Phethai is the sixth named cyclone of 2018 North Indian Ocean Cyclone season.

The previous five named cyclones are Sagar, Mekunu, Luban, Titli and Gaza. Cyclone Pethai has emerged as a deep depression in the Bay of Bengal around 900 kms off Chennai on 15 December 2018. It was expected to bring heavy rainfalls in the coastal areas of north Tamil Nadu, Andhra Pradesh, Chhattisgarh and Odisha.