3 min readFeb 2, 2026 12:37 PM IST
Light rain in several parts of NCR and calm winds overnight triggered dense fog across Delhi on Monday, prompting the India Meteorological Department (IMD) to first issue a red alert in the wee hours. This was later scaled down, and a yellow alert now remains in place for the forenoon hours.
As a result of the dense fog stretching late into the morning, the visibility dipped to as low as 100 m for several hours at Safdarjung and Palam.
The weather conditions, however, helped improve Delhi’s air quality as it turned to ‘Moderate’ (181 AQI) by Monday morning, after the daily average AQI was reported at 265 in the ‘Poor’ range on Sunday.
February, meanwhile, is expected to remain warmer and relatively dry.
What led to the dense fog?
Senior meteorologists attributed the fog formation to stable atmospheric conditions created after the overnight rain spill. High moisture levels coupled with very weak winds allowed cool air to be trapped near the ground, resulting in condensation to fog.
“After the overnight rain, there were only very light winds which didn’t allow the moisture to disperse. This is why, earlier when rainfall was heavier on January 23 and 27, no such fog was seen because stronger winds had prevented it,” said R K Jenamani, senior scientist and head of weather forecast services in IMD.
On Sunday, moisture-laden easterly winds of up to 15 kmph were recorded, which increased humidity across the region.
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According to the IMD Meteorological Centre, Lucknow, the overnight rain was observed in parts of NCR, including Gautam Buddha Nagar (1 mm), Meerut (5 mm), Muzaffarnagar (6 mm) and Agra (2.2 mm). There was no rainfall recorded in Delhi.
Impact of ‘feeble western disturbances’: No rain, increase in temperature
The IMD has said that a fresh feeble western disturbance is likely to affect the higher reaches of the Himalayan region from Monday night. Another western disturbance is expected to impact northwest India from the night of February 5.
Dr Mrutyunjaya Mohapatra, Director General (IMD), had earlier on Saturday said that Northwest India, including Delhi, would see higher day and night temperatures because of “weaker western disturbances”. He said the cloud cover will lead to increase in night temperatures, but a lack of rain would result in warmer days.
What has the IMD forecast for the week?
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The IMD said there is no alert for the remaining days of the week, during which shallow to moderate fog is expected along with partly cloudy skies.
The temperatures are forecast to rise by the weekend and would remain in the range 9-11 degrees Celsius to 22-24 degrees Celsius.
Cold, dry northwesterly winds below 10 kmph, which is not for dispersal of pollutants will also lead to an increase in pollutant profile.
The air quality is forecast to be in the ‘Poor’ range, wherein the AQI is between 201-300, according to the Indian Institute of Tropical Meteorology.
