Besides Nellore, Prakasam, Guntur and Krishna districts are also likely to be badly hit by the storm. Wind speeding upto 120 kmph and heavy rainfall are predicted in these coastal districts. North coastal Tamil Nadu and Puducherry are also expected to see an adverse weather.
The cyclone is currently located about 430 kilometre east of Kavali, 470 km east-northeast of Chennai and 290 km of south-southeast of Visakhapatnam.
Fishermen have been warned against travelling into deep sea.
Helen is the second cyclonic storm set to hit Andhra in as mny months
Last month, a severe cyclonic storm called Phailin, the second strongest since the deadly super-cyclone that had hit Odisha in 1999, hit Andhra Pradesh and Odisha, causing massive damages. The death toll was, however, not huge and the Indian disaster-fighting forces received a pat on their back for dealing with the Phailin's aftermath.