A well-marked low pressure has formed in the Bay of Bengal and is expected to intensify into a depression in the next 36 hours, the Regional Meteorological Department said on Sunday.
The weather office has cautioned fishermen against venturing out to the South and Central areas of Bay of Bengal till October 9.
"A new low pressure has formed North of the Andaman (and Nicobar Islands) and South east of the Bay of Bengal. This is expected to further intensify into a depression and move towards the Odisha coast in the next 72 hours," RMD Deputy Director General S Balachandran told reporters.
Under the influence of the low pressure, most places in Tamil Nadu registered moderate rainfall in the last 24 hours ending 8.30 am on Sunday, while Mimisal, a coastal village in Pudukottai district, received 13 cms of rainfall.
Sankarankovil and Ambasamudram received 8 cm each, Tiruppur and Tenkasi 7 cm each, while Kothagiri, Senkottai, Pudukottai and Tiruppuvanam each received 6 cm of rainfall, Balachandran said.
For the next 24 hours, moderate rainfall is expected in several parts of Tamil Nadu and Puducherry while places like Kanyakumari, Tirunelveli, Dindigul, Theni might receive heavy rainfall, he said.
For Chennai and its neighbouring areas, there may be light to heavy rainfall in some places in the next 24 hours.
The prevailing climatic conditions favour the onset of the northeast monsoon in the state, Balachandran said.
The RMD deputy director general said the deep depression in the South Arabian Sea presently lay 920 km North West of Minicoy Islands of Lakshadweep and was expected to intensify into a cyclone in the next 24 hours and move towards Oman.
Fishermen have been advised not to venture into the South and Central Arabian Sea till October 12, he said.