The India Meteorological Department (IMD) announced on Monday the southwest monsoon has started withdrawing from India, eight days after the normal date of September 17.
The late retreat of the monsoon this year is the 13th consecutive delayed withdrawal. India is divided into 717 meteorological districts, of them 221 have received deficit rainfall while 492 received normal or excess rainfall so far.
India received 796.3 mm rainfall as against the normal of 843.2 mm, deficit of 46.8 mm amounting to 6 percent. Nearly 2 per cent of rainfall needs to be offset in the remaining 6 days of the month, for the monsoon season to turn ‘normal’.
Rainfall between 94 per cent and 106 per cent of the long-period average (LPA) is considered normal. Bihar, Gangetic West Bengal, Jharkhand, Arunachal Pradesh, Sikkim, Kerala, East Uttar Pradesh, Mahe, South Karnataka and Lakshadweep among the states which received less monsoon rain this year.
Typically, the southwest monsoon makes its onset over Kerala by June 1 and covers the entire country by July 8. It starts retreating from northwest India around September 17, withdrawing entirely by October 15.
“(The) southwest monsoon has withdrawn from parts of southwest Rajasthan today, September 25, 2023, against its normal date of withdrawal from southwest Rajasthan of September 17,” IMD said in a statement.
For withdrawal of monsoon, the IMD considers certain conditions to be fulfilled, including dry weather over an area for five consecutive days, a considerable reduction in moisture content as inferred from satellite water vapour imageries and tephigrams and an anticyclone in the lower levels of the atmosphere.Normally, the country receives an average of 870 mm of precipitation during the four-month monsoon season (June to September).
Withdrawal of the monsoon from northwest India marks the beginning of its retreat from the Indian subcontinent. Any delay in the monsoon’s retreat means a longer rainy season, which can significantly impact agricultural production, particularly for northwest India where monsoon rainfall plays a crucial role in the Rabi crop production.
The onset month of June remained 10% below the normal. This shortfall was made up in July when the month accumulated a surplus of 13% rainfall. The monsoon rainfall was 105 per cent of LPA at the halfway mark of the season. And then, there was a collapse. With prolonged break-monsoon conditions, the core monsoon month of August slumped miserably to be the lowest on record since the time record-keeping began.