The system is now headed north-northwest, he said. It will weaken further into the 'cyclonic storm' category by Sunday afternoon and then into a deep depression by evening.
The weakened system will traverse Bihar and parts of eastern Uttar Pradesh by Tuesday, before moving to Nepal, whose rivers can trigger flooding in Bihar.
Rathore said the timely evacuations in the state had resulted in "zero loss of lives" due to Phailin, the worst storm to hit India in 14 years.
The threat has now shifted to flooding in states like Jharkhand, West Bengal, Chhattisgarh and Bihar, which have been put on alert.