The India Meteorological Department (IMD) has issued a ‘yellow’ alert for Delhi, warning of dense fog that is likely to affect visibility across the national capital on Saturday morning. The alert comes amid a spell of cold weather, with the weather office also forecasting cold wave conditions at isolated places in the city between January 3 and January 6.

According to the IMD, dense fog during the early morning hours could disrupt road, rail and air traffic, a recurring winter concern for Delhi and the surrounding National Capital Region (NCR). The alert advises commuters to remain cautious, especially during early morning travel, when visibility levels are expected to be significantly reduced.

Alongside the fog warning, the IMD said Delhi is likely to experience colder-than-usual conditions over the next few days. A cold wave is declared when the minimum temperature falls between 4.5 degrees Celsius and 6.5 degrees Celsius below the seasonal average. While the city has not uniformly entered cold wave conditions yet, isolated pockets may be affected during the January 3–6 period, particularly during the night and early morning hours.

On Friday, Delhi recorded a noticeable improvement in air quality, offering temporary relief after several days of severe pollution. The city’s 24-hour average Air Quality Index (AQI) stood at 236, placing it in the ‘poor’ category. This marked a significant improvement from Thursday’s AQI of 380, which fell under the ‘very poor’ category.

Weather conditions on Friday reflected the onset of winter chill. The maximum temperature in Delhi settled at 17.4 degrees Celsius, nearly two degrees below the normal for this time of year. The minimum temperature was recorded at 9.1 degrees Celsius, which was about 2.2 degrees above the seasonal average, indicating relatively milder nights compared to previous cold spells.

Station-wise temperature data showed some variation across the city. Lodhi Road recorded a maximum temperature of 17.4 degrees Celsius, followed closely by Ayanagar at 17.2 degrees Celsius. The Ridge area was cooler, with a maximum temperature of 14 degrees Celsius, while Palam registered 16.4 degrees Celsius. Minimum temperatures ranged from 9 degrees Celsius at Palam and Lodhi Road to 8.7 degrees Celsius at the Ridge and 8.1 degrees Celsius at Ayanagar.

For Saturday, the IMD has forecast a minimum temperature of around 7 degrees Celsius and a maximum of about 18 degrees Celsius. Dense fog is expected during the morning hours, which could reduce visibility and impact travel plans. As the day progresses, conditions are likely to improve slightly, with clearer skies and marginal warming.

Visibility levels have already shown signs of fluctuation. Safdarjung, one of Delhi’s key weather stations, recorded the lowest visibility of 800 metres between 1.30 am and 2 am on Friday. Visibility later improved to around 1,200 metres by 2.30 am, underscoring how rapidly fog conditions can change during winter nights and early mornings.

Air quality across the city also showed mixed trends through the day. Data from the Central Pollution Control Board’s (CPCB) SAMEER app indicated that, as of Friday evening, 15 monitoring stations were in the ‘moderate’ category, 20 were in ‘poor’, and one station was in the ‘very poor’ category. NSIT Dwarka recorded the worst AQI reading of 367 in the evening hours.

Earlier in the morning, air quality had remained in the ‘very poor’ category, with an AQI reading of 302. According to CPCB standards, an AQI between 201 and 300 is considered ‘poor’, while readings between 301 and 400 fall in the ‘very poor’ range. An AQI of 401 or above is classified as ‘severe’, posing serious health risks.

The Decision Support System (DSS) for air quality management showed that transport emissions were the largest contributor to Delhi’s pollution load on Friday, accounting for 11.11 per cent. Peripheral industries contributed 8.4 per cent, while residential sources accounted for 2.8 per cent. Construction activities contributed 1.4 per cent, and waste burning accounted for around one per cent of the pollution load.

Pollution from neighbouring NCR districts also continued to influence Delhi’s air quality. Muzaffarnagar accounted for 7.5 per cent of the overall contribution, followed by Baghpat at 8.2 per cent and Sonipat at 7.1 per cent. Meerut contributed 4.2 per cent, Jhajjar 3.4 per cent, Gautam Budh Nagar 2.2 per cent, and Ghaziabad 1.8 per cent.

Despite the improvement seen on Friday, authorities remain cautious about the days ahead. The Air Quality Early Warning System has forecast that air quality is likely to remain in the ‘poor’ category from Saturday and may deteriorate to ‘very poor’ levels between January 4 and January 5, depending on meteorological conditions such as wind speed, temperature inversion and fog intensity.

In response to the improving trend, the Commission for Air Quality Management (CAQM) in NCR and adjoining areas on Friday revoked restrictions imposed under Stage III of the Graded Response Action Plan (GRAP). These curbs had been enforced when air quality deteriorated sharply earlier in the week.

“The AQI of Delhi, which was recorded as 380 on Thursday, has significantly improved and was recorded at 236 at 4 pm on Friday, exhibiting a sustained improving trend,” an official statement said. “Keeping in view the prevailing trend of air quality, the CAQM Sub-Committee on GRAP decides to revoke all actions as envisaged under Stage III of the extant GRAP, with immediate effect, in the entire NCR.”

However, the relaxation is partial. The CAQM clarified that preventive and restrictive measures under Stages I and II of GRAP will continue to remain in force across the NCR. These include curbs on dust-generating activities, regulation of construction work, and advisories to reduce vehicular emissions, among others.

As Delhi heads into the first week of January, residents are likely to face a combination of dense fog, cold wave conditions in pockets, and fluctuating air quality. While the recent improvement in pollution levels has provided some respite, meteorologists and pollution experts warn that winter weather patterns could quickly reverse the gains. Authorities have urged citizens to remain vigilant, follow advisories, and take precautions to protect themselves from both cold conditions and air pollution in the days ahead.