Grey skies and misty mornings in the last few days, accompanied by heavy rain and a chill in the air, may have made residents of Delhi feel like they are heading towards an early winter. However, the skies are expected to clear soon, marking a return to warmer days. Delhi on Wednesday recorded a maximum of 26.5 degree Celsius, around eight degrees below normal, while the minimum was at 20.3 degree Celsius, a notch below normal. However, according to India Meteorological Department's (IMD) six-day forecast issued on Wednesday, the skies will mainly remain clear, with maximum temperatures likely to hover between 33 degree Celsius and 35 degree Celsius and the minimum between 20 degree Celsius and 22 degree Celsius. The reason for this chill in the air has been due to the city already logging 90 mm of rainfall in October - nearly six times the normal of 15.1 mm. So what caused the unusually wet October? The unusual rainfall, along with the dip in day temperature, is the result of local western disturbances, said meteorologists. According to IMD officials, "high moisture feeding" from the Arabian Sea over Northwest India in the lower tropospheric levels and parts of Himachal Pradesh as well as Jammu and Kashmir already receiving the first flakes of snow this week led to a change in weather pattern this month. IMD Director General Mrutyunjay Mohapatra said the extended wet phase is linked to the delayed monsoon withdrawal and the development of rain-bearing low-pressure systems. A depression that remained over the west-central Arabian Sea, a remnant of Cyclonic Storm Shakhti, moved east-southeastwards and weakened into a low-pressure area on Tuesday, leading to widespread rainfall across parts of North India, the IMD said on Wednesday. “The low-pressure region extending to the Arabian Sea was active for 4-5 days, and only now its intensity has subsided. That’s why rainfall activity is not expected in the coming days. The temperatures will rise in the coming days now that the western disturbance has weakened,” said Krishna Mishra, senior IMD official. Mahesh Palawat, vice president (Meteorology and Climate Change) at Skymet Weather, said the unusual rain and early snow were a result of multiple interacting weather systems. “This year, as the Western Disturbance was over the western Himalayas and remnants of cyclonic circulation with low-pressure systems reached up to north India, a combination of these circulations and moisture-laden winds from the Arabian Sea and Bay of Bengal led to early snowfall and unusual rain,” he said. Palawat added that while winter could set in slightly earlier than usual, it is unlikely to be severe. “La Niña hasn’t developed yet. It may be a short-period La Niña before the onset of the next monsoon, after which conditions will again turn neutral,” he added. La Niña is the cool phase of a natural climate pattern across the tropical Pacific known as the El Niño Southern Oscillation (ENSO), which generally leads to below-normal temperatures. Globally, climate models have forecast the development of a weak La Niña in the post-monsoon season this year. “Currently, sea surface temperatures over the equatorial Pacific are near average, indicating neutral ENSO conditions. Forecasts from the Monsoon Mission Coupled Forecast System (MMCFS) and other climate models suggest an increased likelihood of La Niña conditions developing during the post-monsoon season,” the IMD said. The National Oceanic and Atmospheric Administration, an agency of the US government that works to understand and predict changes in climate, weather, oceans, and coasts, said: “A transition from ENSO-neutral to La Niña is likely in the next couple of months, with a 71% chance of La Niña during October–December 2025. Thereafter, La Niña is favored, but chances decrease to 54% in December 2025–February 2026.” According to weather experts, not just La Niña but multiple factors like Arctic winds, frequency, intensity, and passage of western disturbances contribute to the severity of winter. Officials in IMD said the neutral phase of ENSO is likely to transition briefly into a weak La Niña before turning neutral again ahead of the next monsoon. In its seasonal outlook issued earlier this month, the IMD had projected above-normal rainfall for most parts of the country in October, except Jammu and Kashmir and the southernmost regions of Kerala and Tamil Nadu.
