According to the weather department the cyclone lays centered over coastal Tamil Nadu and Puducherry about 25km north of Puducherry with wind blowing at a speed of 90-100 kmph gusting to 110 kmph.
Nivar will move northwest wards and weaken further into a cyclonic storm during the next three hours, the IMD said.
The sea along the coast is very rough with huge waves hitting the shores.
Under its influence rainfall at most/many places with heavy to very heavy downpour at a few places with isolated extremely heavy rainfall likely to occur over Ranipet, Tiruvannamalai, Tirupattur, Vellore districts of Tamilnadu and Chittoor, Kurnool, Prakasam and Cuddappa districts of Andhra Pradesh on November 26.
The Tamil Nadu and Puducherry government have announced Thursday as public holiday.