The Southwest Monsoon made an onset over Kerala on Thursday after a delay of two days, the India Meteorological Department said.
The monsoon onset over Kerala marks the commencement of the four-month rainfall season in the country.
"The Southwest Monsoon has made an onset over southern parts of Kerala," IMD Director General Mrutunjay Mohapatra was quoted saying by news agency PTI.
The normal onset date for Southwest Monsoon over Kerala is June 1.
Releasing its second long range forecast for southwest monsoon on Tuesday, the IMD said it is likely to be normal in north and south India, above-normal in central India and below-normal in east and northeast India.
Overall monsoon this year is likely to be normal in the country as a whole, Mrutunjay Mohapatra had said.
"We are expecting a good monsoon which will help the agriculture sector," Mohapatra said in an online briefing.
"Quantitatively, the monsoon seasonal (June to September) rainfall over the country as a whole is likely to be 101 per cent of the Long Period Average (LPA) with a model error of plus or minus four per cent," he said.
Rainfall in the range of 96-104 of the LPA is categorised as normal. The LPA of the season rainfall over the country as a whole for the period 1961-2010 is 88 cm.
In its first long range forecast for southwest monsoon 2021, the IMD had predicted rainfall to be 98 per cent of the LPA which also falls under the normal category. But it has not upgraded its forecast to 101 per cent of the LPA which is on the higher side of the normal range.
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.
"The southwest monsoon seasonal (June to September) rainfall over the four homogeneous rainfall is most likely to be normal over northwest India (92-108 per cent) and south peninsula (93-107 per cent). Seasonal rainfall is most likely to be below normal over northeast India (106 per cent)," the IMD said.
He said spatial distribution suggests normal or above normal seasonal rainfall is most likely over many areas of northwest and central India, and eastern parts of southern peninsula.
Below normal seasonal rainfall is most likely over some areas of north, east, northeast parts of the country and western parts of the south peninsula, he said.
Mohapatra said the latest global model forecasts indicate the prevailing neutral ENSO conditions are likely to continue over the equatorial Pacific Ocean and possibility of development of negative Indian Ocean Dipole conditions over the Indian Ocean during the monsoon season.
El Nino, La Nina, positive and negative IOD are believed to have an influence over the Indian monsoon. El Nino and La Nina are associated with the heating and cooling of the equatorial Pacific Ocean respectively. Negative and positive IOD are also linked to the heating and cooling of the Indian Ocean waters respectively.
