Delhi: IMD predicts rain this weekend, colder days

Delhi experienced dense fog with visibility dropping to 100m on Thursday, while temperatures rose slightly. Rain is forecast for the weekend, affecting air quality.

A thick blanket of fog enveloped Delhi on Thursday morning, even as the temperature saw a slight uptick with both minimum and maximum temperatures remaining above normal, scientists said.

A municipal sweeper at Patel Nagar, amid a thick layer of fog on Thursday morning. (Sanchit Khanna/HT Photo)

The India Meteorological Department (IMD) has forecast rain and thundershowers over the weekend, and said that the mercury might see a slight dip thanks to the impact of the western disturbance (WD) on Friday, Saturday and Sunday.

Safdarjung, which is representative of the entire city, recorded a minimum of 8.2 degrees Celsius (°C) and a maximum of 24.1°C, slightly higher than Wednesday’s maximum of 22.4°C. While Thursday’s minimum temperature was a degree above normal, the maximum was three notches above normal.

Dense fog was reported at Safdarjung with visibility dropping to as low as 100metres. The fog persisted until around 8.30am, affecting flight and train schedules but causing no diversions. Palam airport reported moderate fog, with visibility dropping to 300m before improving quickly.

IMD defines “shallow” fog in a region when visibility drops to 500-1,000m, “moderate” fog when visibility is 200-500m, “dense” fog when visibility is 50-200m, and “very dense” when visibility dips to 50m or lower.

Officials added that a WD is likely to impact Delhi-NCR causing rainfall and lower temperatures over the next three days. As per the forecast, smog and moderate fog can be expected in the morning with generally cloudy sky.

“A western disturbance is very likely to interact with lower levels easterly winds over central parts of the country leading to high moisture feeding from Arabian Sea as well as Bay of Bengal mainly during December 27 and 28. This is likely to cause rain spells over NCR the next few days,” another IMD official said.

This is expected to cause a slight dip in temperatures, the official said.

The 24-hour average air quality index (AQI) on Thursday was recorded at 345 (“very poor”) at 4pm, according to the Central Pollution Control Board’s daily national bulletin. The AQI has been in the “very poor” category for three consecutive days now. It was last in the “severe” category on December 23 at 406. Last week, the AQI had stayed in the “severe” category for four consecutive days, making it the worst since December 2021.

According to the Air Quality Early Warning System (AQEWS) for Delhi, the predominant surface wind on Thursday was mostly from the northeast direction. While the wind speed was around 4kmph, it is likely to improve due to the WD ushering in rain over the next few days.

Gusty winds with the speed of 30-40kmph is also likely at isolated places on Friday, according to the AQEWS, which may also aid dispersal of pollutants and bring pollution levels down to poor.

“The air quality is likely to be in poor category on Friday and may become moderate on Saturday. It is likely to be in poor category on Sunday. The outlook for subsequent six days is that the air quality is likely to be in poor to very poor category,” according to AQEWS.