The monsoon onset over Kerala marks the commencement of the four-month rainfall season in the country.
However, there was no report of any major damage or casualty so far even as the landfall process started more than an hour ago, the official said.
IMD Director General Mrutunjay Mohapatra said the department's modelling indicate formation of a cyclonic storm around May 9, but its movement and intensification may be determined after the low pressure area actually forms on May 7.
The IMD DG said there should not be an impression that climate change leads to rise in the temperature, but on the contrary, it leads to erratic weather.
As Odisha and West Bengal are bracing for a severe cyclonic storm, governments of both states started evacuating people and while deciding to close educational institutions in vulnerable areas.
A total of 435 people died in the country due to extreme weather events during the last three months of the southwest monsoon, according to the data compiled by the India meteorological department.
The low-pressure area over the South Andaman Sea and adjoining southeast Bay of Bengal is very likely to move northwestwards and intensify into a depression by Saturday, the weather office said.
The deep depression in the Bay of Bengal is likely to intensify further into a cyclonic storm by late Tuesday night, the IMD said.
The weather system over the South Andaman Sea and the adjoining southeast Bay of Bengal is very likely to move north-westwards and strengthen into a depression by Saturday, the Met Department said.
The IMD had initially predicted that Cyclone Nivar was likely to intensify into a 'severe cyclonic storm' but has now estimated that it will intensify further.
'There was a slight change of direction towards north-eastwards which meant the impact of the cyclone on Mumbai was less severe than originally expected,' the IMD said in a statement.
Scores of people die every year due to cold waves that sweep across the north Indian plains.
Mohapatra said there is a 40 per cent chance of a normal rainfall, 22 per cent above normal, 12 per cent excess and 18 per cent below normal.
'Yaas' is likely to cross the Odisha-West Bengal coasts between Paradip and Sagar Islands around noon on May 26 as a very severe cyclonic storm with wind speeds of 155-165 kmph, Kolkata's Regional Meteorological Centre Deputy Director Sanjib Bandopadhyay said.
The cyclone expected to weaken gradually over the next two days.
IMD director general Mrutunjay Mohapatra said that cyclone Asani has already achieved maximum stage of intensification and is gradually getting weakened.
In another forecast for August, IMD Director General Mrutunjay Mohapatra said monsoon is also likely to be normal in the month.
India received 41 per cent more rainfall than normal from October 1-21 with Uttarakhand alone recording more than five times its normal precipitation, IMD data showed on Thursday.
The southwest monsoon over the country is likely to be normal in July, the India Meteorological Department (IMD) said on Thursday in its forecast for the month.
Some low-lying places like Hindmata, and areas in Dadar and Sion, including the Gandhi Market and road number 24 in Sion, were inundated, forcing pedestrians to wade through the water and making it difficult for motorists to commute.
With cyclone Phailin expected to make landfall in Odisha on Saturday, the state government mounted a massive operation to evacuate two lakh people from six coastal districts on Friday night