Fearing further damage and loss of lives and property during the cyclone, the army, air force and navy, besides the Disaster Management Response Force, have been kept on standby.
Under the influence of a depression over the Bay of Bengal that is threatening to unleash a cyclonic storm, rains and thundershowers would occur at most places, from Saturday morning, weather office said.
Isolated heavy to very heavy rainfalls were also expected over north Tamil Nadu and south Andhra Pradesh coasts, it added. Wind speeds could touch 65 kmph, and commence along and off north Tamil Nadu and south Andhra Pradesh coast, the weather office said in a statement.
Sea conditions will be rough to very rough, and fishermen have been advised against venturing into the sea.
"The depression over southeast Bay of Bengal is likely to intensify into a cyclone and move west-northwestwards towards north Tamil Nadu and south Andhra Pradesh coast during next 72 hours," the Indian Meteorological Department statement said.
"Latest satellite imagery indicates that a depression has formed over southeast Bay of Bengal and lay centred at 0530 hrs IST of 4th November, 1150 km east of Batticaloa, 1400 km east-southeast of Chennai and 1450 km southeast of Visakhapatanam," the statement explained.
Heavy rains, caused by low pressure over Bay of Bengal and vigorous northeast monsoon, have caused widespread devastation in six districts of coastal Andhra. Officials said the rains have claimed 26 lives in four days, though the downpour has stopped now. Nearly 600,000 people in 1,000 villages and two towns have been affected, and standing crops over seven lakh acres were damaged, dashing the farmers' hopes of a bumper crop this season.
About 50,000 people were shifted to 110 relief camps in the affected districts. More than 126,000 houses were submerged. Chief Minister K. Rosaiah is scheduled to conduct an aerial survey of the affected areas in East Godavari and Krishna districts Thursday.