Here are the latest updates
Experts say the wind speed is at 200 to 210 km per hour and is expected to touch 230 km per hour when the cyclone hits the coasts of Odisha and northern Andhra Pradesh. However, the US Navy says winds may reach 315 kmph on windfall, classifying Phailin as a Category 5 storm - the most powerful.
The National Disaster Management Authority (NDMA) says 1.2 crore people will be affected by the cyclone. "Have to accept the situation has worsened from what we had anticipated. Things have changed from the bulletin we received last evening," said NDMA Vice Chairman M Shashidhar Reddy.
The Indian Meteorological Department or IMD has said Phailin will remain a "very severe" cyclone, but it is not right to call it a super-cyclone yet. "Super cyclone is above 220 kmph and gusting upto 250, so this is touch and go. We are monitoring closely and don't expect further intensification," said Dr LS Rathore, Director General, IMD.
Odisha, which faced the destruction and devastation of 1999's super-cyclone, says it is not ready to take any chances this time around. Odisha's Disaster Management Minister Surya Narayan Patra told NDTV, "We are fighting against nature. We are better prepared this time, we learnt a lot from 1999." Nearly 15,000 people died in the super-cyclone that ravaged Odisha in 1999.
The Odisha government has mounted a massive operation to evacuate two lakh people from six coastal districts. Nearly a lakh of people have already been evacuated from Ganjam, Puri, Jagatsinghpur and Kendrapara districts.
Stocks of food grain and other essential commodities are being put together in cyclone relief centres in Odisha so that people do not face difficulties. Arrangements are being made to provide people cooked food at relief centres.
Odisha and Andhra Pradesh have been warned about extensive damage to homes, communication and power systems and crops in the storm, presaged by heavy rain and strong winds today. 64,000 people have been evacuated from Andhra Pradesh, Chief Minister Kiran Kumar Reddy told NDTV.
Defence Minister AK Antony has asked the Army, Navy and Air Force to be ready for emergency and relief operations. Two Indian Air Force IL-76 aircraft have already airlifted 30 National Disaster Response Force (NDRF) teams, with equipment like ropes, rafts and tree cutting tools. The Indian Air Force, fully geared up, has also put its choppers on standby and is ready to swoop in with relief.
Paradip Port, one of the 12 major ports in the country, has shut all cargo operations, plants and machinery and put in place a contingency plan to meet any eventuality due to Cyclone Phailin. Paradip Port serves the eastern and central parts of the country and its hinterland extends to Odisha, Jharkhand, Chhattisgarh, West Bengal, Madhya Pradesh and Bihar.
Five districts are preparing for the worst impact of the cyclone: Srikakulam in Andhra Pradesh and Ganjam, Puri, Khordha and Jagatsinghapur in Odisha. An official in Ganjam told NDTV that six lakh people could be severely affected in the district.