Slightly warmer temperatures are in store for most parts of the country including northwest India beginning September 19, the government’s official extended weather outlook said, as climatic indications suggest the monsoon could begin withdrawing from northwest India by September 22.
If the prediction come to bear, the rainy season will have begun its earliest withdrawal in eight years, and experts said that this will be followed by a brief uptick in temperatures before days and nights start to become colder for the autumn from early October.
“Temperatures will remain below normal until September 19 but will be slightly above normal after that,” said M Mohapatra, director general, India Meteorological Department, which expected rains to gradually decline over northwest India after September 19.
The extended range forecast shows lower possibility of rain over most parts of the country except east India during the week of September 26 to October 3.
The first half of the month has been unusually rainy for several parts of north India. Since June 1, the country has seen an 8% excess in overall rainfall, but with regional variations: there is a 7% excess in the northwest, 18% in central, 20% in south peninsula, and a 15% deficiency in east and northeast zones.
Officials are now watching for how the autumn unfolds in the coming month, especially in a year when the El Nino to La Nina switch is expected to influence the country’s weather. “Arrival of cooler conditions or winter depends upon how mid-latitude western disturbances move in. In a La Niña year we should expect cooler autumn and winters,” said M Rajeevan, former secretary, ministry of earth sciences.
El Nino and La Nina refer to temperature cycles that unfold in the Pacific Ocean, which has a ripple effect on global weather. El Nino is when the equatorial pacific is warmer than usual, a phenomenon that leads to drier conditions in India. The La Nina does the opposite.
A second expert said monsoon is expected to withdraw by the end of this month. “It seems like temperatures will start dropping soon after once winds change to northerly direction. But whether it will be cold or only a marginal drop we cannot say because that depends on when western disturbances start impacting the northern region,” said Mahesh Palawat, vice president, climate and meteorology at Skymet Weather.
Western disturbance refers to storms that sweep in from the Mediterranean, bringing rain to the plains and snow to the Himalayas, which in turn lead to colder winds in northern India.
Last year, the monsoon started withdrawing only around September 25, and in 2022, around September 30. There is presently a deep depression over Gangetic West Bengal, which is likely to move in a north-west direction. Once it moves inlands, it is predicted to cause isolated very heavy to extremely heavy (over 20 cm) rainfall over Jharkhand, Gangetic West Bengal, Odisha and Bihar till Monday.