With changing rainfall pattern, the Indian Meteorological Department (IMD) will change the reference dates for onset and withdrawal of southwest monsoon from this year, the Ministry of Earth Sciences said on Wednesday.
Secretary in the ministry M Rajeevan said the change in the dates will help farmers who can take a call on sowing crops.
The four-month monsoon season is from June 1 to September 30.
June 1 is the onset date for monsoon over Kerala and it is likely to remain the same but the IMD will change the reference dates for some states and cities, Rajeevan said, adding the dates for withdrawal of monsoon will also be changed.
The onset dates are expected to be changed over the central India meteorological division of the IMD.
The central India division comprises 10 sub-divisions -- Chhattisgarh, Odisha, west Madhya Pradesh, east Madhya Pradesh, Vidarbha, central Maharashtra, Konkan and Goa, Gujarat region and Kutch and Saurashtra.
The new dates are expected to be announced in April when the IMD releases its First Long Range Forecast for Monsoon 2020, IMD Director General M Mohapatra said.
Monsoon starts withdrawing from northwest India (parts of Rajasthan) from September 1.
"This may be shifted to September 10," Rajeevan said.
He said the data cited to give the reference dates dates back to 1940s and it needed to be revised.
He, however, did not specify whether climate change was behind setting the new reference dates.
Last year, the monsoon covered the entire country by July 19, four days after its normal date. It also withdrew from the entire country on October 9, as against the normal date of September 1.
Rajeevan added the IMD is working with the UK's Met department to come up with impact-based forecast that will suggest measures to be taken during extreme weather events.