Delhi’s Deep Freeze: A Chilling Start to Winter and the Cold Reality of Pollution 

Delhi is experiencing its coldest November in five years, with average minimum temperatures plunging to 11.5°C and a recent low of 8°C, due to the influence of La Niña conditions and a lack of moderating weather patterns, which have allowed cold, dry winds to dominate. The India Meteorological Department forecasts that this chill will intensify, with temperatures expected to drop further to around 5°C in the coming days, accompanied by morning fog.

This cold snap has triggered a yellow alert for the region and poses a dual threat: the cold itself and a sharp deterioration in air quality, as the season’s characteristic temperature inversions trap pollutants near the ground, pushing the Air Quality Index back into the ‘Very Poor’ category and creating serious health and travel hazards for residents.

Delhi’s Deep Freeze: A Chilling Start to Winter and the Cold Reality of Pollution 

A Record-Breaking Chill 

Delhi has shuddered through its coldest November in five years, a stark beginning to a winter that meteorologists warn will be harsher and longer than usual. As December dawns, the India Meteorological Department (IMD) forecasts the mercury will plunge further, with minimum temperatures dipping to around 5 degrees Celsius in the coming days. This early and intense cold snap is more than a seasonal shift; it is a complex interplay of global climate patterns and local environmental challenges, setting the stage for a difficult season for the capital’s 30 million residents. 

The Meteorological Facts: A November for the Records 

The data paints a clear picture of an unseasonably cold month. According to the IMD, Delhi’s average minimum temperature for November settled at 11.5 degrees Celsius, marking the coldest reading since 2020. The chill peaked dramatically on November 30th, when the city recorded a low of 8 degrees Celsius—the coldest November day in three years. The daytime offered little reprieve, with maximum temperatures also falling 1.7 degrees below normal. 

This trend represents a significant departure from recent years. The following table highlights the recent trajectory of November’s average minimum temperatures, underscoring the current year’s notable drop: 

The Driving Forces: La Niña and Local Weather 

This sharp decline is not accidental. Meteorologists point to the emergence of La Niña conditions as a primary driver. This climate phenomenon, characterized by the cooling of surface waters in the central and eastern Pacific Ocean, has a well-documented ripple effect on global weather. For the Indian subcontinent, La Niña typically translates to colder and wetter winters in the north and northwest regions. 

The IMD has acknowledged this influence, noting that weak La Niña conditions are expected to persist through the winter months of December to February. This aligns with their seasonal outlook, which predicts normal to below-normal minimum temperatures across central and northwest India, including Delhi, with an increase of 4 to 5 extra cold wave days. The agency has stated that another cold wave spell is expected to grip parts of northwest and central India from December 3rd. 

Compounding this is a lack of active western disturbances—rain-bearing systems that can moderate temperatures. Their absence has allowed cold, dry winds from the northwest to dominate, leading to clear skies. These clear nights are a perfect recipe for radiation fog, where the earth’s heat escapes rapidly, cooling moist air near the ground until it condenses into shallow fog. The IMD has forecast just such conditions: shallow to moderate fog during morning hours, reducing visibility and intensifying the perceived chill. 

The Inextricable Link: Cold Air and Trapped Pollution 

For Delhi, a drop in temperature is inseparably linked to a surge in air pollution. The city’s winter air quality crisis is a catastrophic synergy between human emissions and meteorological fate. Delhi is geographically trapped in a “meteorological prison“. Nestled on the flat Indo-Gangetic plains, with the Himalayas to the north and the Aravalli range to the south, the city sits in a natural bowl. 

In winter, this topography collaborates with the season to create a deadly scenario. As the ground cools at night, it leads to a temperature inversion: a layer of warmer air acts like a lid over the colder, denser air at the surface. This inversion traps pollutants—from vehicles, industry, construction dust, and seasonal agricultural burning—preventing them from dispersing vertically. The height at which pollutants can mix, known as the “mixing height,” collapses from about a kilometer in summer to just a few hundred meters in winter, concentrating toxins in a much smaller volume of air. 

The result is the capital’s notorious smog. Despite a brief improvement, air quality has swiftly deteriorated back into the ‘Very Poor’ to ‘Severe’ category. On December 1st, the overall Air Quality Index (AQI) was 301, with 24 out of 38 monitoring stations in the city recording ‘Very Poor’ air. This pollution doesn’t just haze the sky; it compounds health risks during the cold, particularly for the elderly, children, and those with respiratory or cardiovascular conditions. 

Forecast and Official Advisories: Bracing for Impact 

The immediate forecast confirms that the deepest chill is still ahead. The IMD predicts minimum temperatures will hover around 5 degrees Celsius over the next four days, with maximums struggling to reach 22-24 degrees Celsius. From December 5th, the clear skies may give way to partly cloudy conditions, but shallow to moderate fog is likely to persist. 

In response to these conditions, the IMD has issued a yellow alert for Delhi-NCR from December 2 to 5. This alert warns residents of the harsh early-winter phase, advising caution due to expected dense fog and cold wave conditions. 

The advisory comes with critical warnings for daily life: 

• Travel Disruptions: Dense morning fog is predicted to severely reduce visibility on major highways and corridors, including NH-44 and the Delhi-Jaipur and Delhi-Meerut Expressways. Travelers should anticipate significant flight delays and railway disruptions, and are advised to avoid early-morning long-distance travel if possible. 

• Health Precautions: Authorities stress the need for vulnerable populations to take extra care. The combination of cold air and high pollution levels increases the risk of respiratory distress, asthma attacks, and cardiovascular events. 

A Season of Challenge and Adaptation 

Delhi’s current weather is a preview of a potentially long and severe winter, shaped by the distant influence of La Niña and amplified by local environmental realities. The record-breaking November cold is just the opening act. As temperatures continue to fall, the city must grapple not only with the physical discomfort of the chill but also with the suffocating blanket of pollution that the winter meteorological trap guarantees. 

This season underscores a brutal truth: for Delhi, the battle for breath is a winter ritual. While long-term solutions require systemic changes to emissions and regional cooperation, the immediate need is for preparedness and protection. The yellow alert is more than a weather notice; it is a directive for millions to adapt their routines, safeguard their health, and navigate a season where the air itself becomes a central adversary. The cold may be a natural phenomenon, but the toxic smog it locks in is a human-made problem waiting for a decisive, collective solution.