Delhi wakes up to coldest September morning in 18 years. What's behind it?

Delhi woke up to an unusually cool and hazy morning on Tuesday, with the minimum temperature falling to 21°C, which is 2.3 degrees below normal.This was the lowest minimum temperature recorded in the capital in September since 2008, according to the India Meteorological Department (IMD).The dip in temperature came after recent rain over Delhi-NCR, as the capital moves through the final phase of the monsoon season and into a drier post-monsoon period.WHY DID DELHI TURN SO COOL?The unusually low minimum came amid a wet spell over the region. The IMD recorded rainfall at many places across Haryana, Chandigarh and Delhi in the 24 hours ending at 5:30 am on Tuesday.The rain, along with cloud cover and moisture in the atmosphere, helped keep nighttime temperatures down. The IMD's observations show that minimum temperatures across Haryana, Chandigarh and Delhi were near normal on September 28, while Delhi recorded the more significant drop by Tuesday morning. A satellite image shows India without any cloud cover. (Photo: IMD) The result was a cooler start to the day for the capital, which is unusual enough to make Tuesday's minimum the lowest September reading in 18 years.The record was broken just days after Delhi recorded a minimum temperature of 21°C on September 27, marking its second-lowest September reading in 25 years and the lowest since 2001.WHY WAS DELHI HAZY?The cool Tuesday morning also came with a layer of haze that softened the city's skyline. An image of a street in New Delhi surrouded by haze. (Photo: X/@adnanbinashraf) The haze followed the recent rain and lingering moisture in the lower atmosphere.Moisture, along with suspended particles near the surface, can make the air appear hazy, particularly during the early morning.However, the IMD bulletin does not identify a specific pollution episode or a single cause for Tuesday morning's haze.The unusually cool September morning does raise questions about whether winter is arriving early, particularly as El Nino conditions develop in the Pacific.But the current cold spell should not be linked directly to El Nino.The recent drop in Delhi's temperature was primarily the result of a prolonged weather system that brought widespread rain, persistent cloud cover and reduced daytime heating across north India. Clouds hover in the sky in New Delhi. (Photo: PTI) MONSOON IS GONE BUT RAIN STILL AROUNDThe southwest monsoon has officially withdrawn from Delhi, but the capital is still seeing the effects of other weather systems.The IMD's latest analysis shows a western disturbance as a cyclonic circulation over south Rajasthan, while upper-air circulations persist over Uttar Pradesh.Watch | Rithala: A change in the weather was observed in Delhi after the rain. On Tuesday morning, fog and mist prevailed in several areas, while a drop in temperature was also recorded. pic.twitter.com/NZbA22YFLf— United News of India (@uniindianews) September 29, 2026For Tuesday, the weather office has forecast isolated to scattered rainfall accompanied by thunderstorms and lightning over Haryana, Chandigarh and Delhi. But the rain is expected to fade quickly.The IMD's weather forecast for the coming days shows isolated rain for Haryana, Chandigarh and Delhi only on September 29, followed by dry weather from September 30 through October 5.So while Tuesday began with a record-cool September morning and a hazy skyline, Delhi is now heading towards a much drier spell, marking another step in the city's transition from the monsoon to the post-monsoon season.- Ends