On the day, Delhi recorded a minimum temperature of 8.4 degrees Celsius (°C). Although it was down from a minimum of 9.9°C recorded a day before, it still was one degree above the normal for this time of the year. The maximum temperature was 22.4°C, two degrees above normal and up from a maximum of 20.8°C recorded a day before.
IMD forecast the minimum to rise up to 11°C by Friday, before dipping again from the next week. It forecast a maximum temperature of 21°C.
An IMD official said, “A moderate fog is likely to form in the morning for the next three days. A dense fog has been forecast for Sunday.”
On Wednesday, a “dense fog” was recorded at the Safdarjung and Palam observatories, with visibility falling to 100 metres between 5.30am and 7.30am.
IMD classifies it a “shallow fog” when the visibility is between 500 metres and 1,000m, a “moderate fog” when visibility is between 200m and 500m, a “dense fog” when visibility is between 50m and 100m, and a “very dense” fog if the visibility falls below the 50-metre threshold.
Elaborating on the reason for issuing a yellow alert from Thursday to Sunday, the IMD official cited above said: “Due to a fresh and more active western disturbance, predicted to start influencing the Capital from Thursday, we might see some very light to light rain towards the evening on Thursday. Weather conditions might get more intense on Friday, when Delhi is likely to experience moderate rain and thunderstorms, accompanied by lightning and gusty winds of speed 30-40 kmph.”
On Wednesday, only two weather stations recorded trace to light rainfall. According to IMD data, Pitampura and SPS Mayur Vihar stations each clocked 0.5mm of rainfall between 5.30am and 8.30am. There was no rainfall at any other station later in the day.
Air quality improves
The light drizzle late on Tuesday evening and an increase in wind speed help improve Delhi’s air quality.
Delhi recorded a 24-hour average air quality index of 336 (“very poor”) on the day, which was better than the previous 24-hour average of 369 (“very poor”)—when the fourth stage of the graded response action plan (Grap 4) was revoked by the Commission for Air Quality Management (CAQM)—according to the Central Pollution Control Board’s (CPCB’s) daily bulletin.
The Air Quality Early Warning System (AQEWS) for Delhi, meanwhile, forecast the air quality to stay in the “very poor” category on Thursday, but predicted an improvement thereafter.
The air quality this month has been a story of two halves. Until December 15, the AQI was relatively cleaner than other years, recording “moderate” or “poor” AQI except for December 8, when it recorded an AQI of 302 (“very poor”).
Then, a four-day streak of “severe” air was recorded from December 17 to December 20, forcing the imposition of Grap Stage 4, under which schools declared hybrid classes for all classes, non-emergency commercial vehicles were banned and work timings were staggered to reduce vehicular pollution on roads. The six “severe” air days in a seven-day period between December 17 and 23 was the highest since 2021, when six consecutive “severe” aid days were recorded.
CPCB classifies AQI between 0 and 50 as “good”, between 51 and 100 as “satisfactory”, between 101 and 200 as “moderate”, between 201 and 300 as “poor”, between 301 and 400 as “very poor”, and over 400 as “severe”.
“The air quality is likely to be in ‘very poor’ category on Thursday. The air quality is likely to be in ‘poor’ category on Friday and ‘moderate’ category on Saturday. The outlook for subsequent six days is that the air quality is likely to be in ‘moderate’ to ‘poor’ category,” the AQEWS bulletin said on Wednesday evening.
