1.4°C: Cold wave hits Capital,brings coldest night in 2 years

Frosty winds brought in a cold wave to the national Capital with night temperatures plunging close to 1°C at several of the city’s 13 weather stations, but clear skies and bright sunlight during the day helped Delhi shake off the chills to some degree.

The city’s base station, Safdarjung, recorded 1.4°C, the lowest since January 1, 2021 when it was 1.1°C. Six notches lower than normal, the reading qualified for a cold wave, which is declared once the negative deviation is 4.5°C or more.

Had the temperature been lower by another half a degree, it would have been classified as a severe cold wave.

Monday’s minimum was the third day the mercury plummeted drastically, from a minimum of over 10 degrees on Saturday, to 4.7°C on Sunday.

RK Jenamani, scientist at the India Meteorological Department, attributed the phenomenon to a combination of strong cold northwesterly winds, clear skies, and low moisture content in the air. “Clear skies generally lead to high maximum and low minimum, as more heat reaches the surface during the day and, at night, the absence of clouds means this same heat is lost very quickly. We are also seeing strong winds of 10-20 km/hr, while Delhi’s moisture content, particularly in the afternoon is around 30%. This was over 60% three days ago — high moisture also helps regulate temperature by trapping heat, similar to clouds,” Jenamani said.

The IMD has forecast a cold wave to continue in the region over the next two days, with Delhi’s minimum oscillating between 1-2°C at Safdarjung, while it may dip even lower at other locations.

This is Safdarjung’s sixth cold wave day in January this year, with the five others coming consecutively between January 5 till January 9. It was Delhi’s longest such spell for the month since 2013.

In comparison to the minimum, Delhi’s maximum showed a slight rise, touching 18.7°C — a notch below normal. The day temperature was 17.8°C on Sunday. Forecasts show Delhi’s maximum is likely to hover around 19 degrees on Tuesday and Wednesday, helping mitigate the cold to some extent.

These strong northwesterly winds also kept Delhi’s air quality in poor category — an improvement from the very poor and severe recorded in recent weeks — on Monday morning, despite slight deterioration compared to Sunday. The capital recorded an Air Quality Index (AQI) of 270, according to Central Pollution Control Board’s national bulletin released at 4pm on Monday. The AQI was 213 (poor) on Sunday and 353 (very poor) on Saturday.

The improvement in air quality prompted the Commission for Air Quality Management (CAQM) in NCR and Adjoining Areas to revoke measures under Stage III or the severe category of the Graded Response Action Plan (Grap) on Sunday. Private construction activities, brick kilns, hot mix plants not operating on clean fuels, stone crushers, mining, and its associated activities are now allowed again.

Forecasts by the Early Warning System (EWS), used by CAQM to take pre-emptive action, show Delhi’s AQI is likely to return to “very poor” by Tuesday, owing to low temperatures. An AQI between 0-50 is considered good, 51 and 100 satisfactory, 101 and 200 moderate, 201 and 300 poor, 301 and 400 very poor, and over 400 severe.

“Delhi’s air quality is likely to remain in the ‘poor’ category on January 16 and deteriorate and reach the lower end of the ‘very poor’ category on January 17. The air quality is likely to deteriorate further but will still remain in the ‘very poor’ category from January 18 to 19,” said EWS.

The Capital’s weather was still a shade better than the biting cold in Rajasthan, Punjab and Haryana.

Faridkot and Bathinda were the coldest places in Punjab with a minimum temperature of 0.2 degrees Celsius each, according to the Meteorological Department here.

In Haryana, Hisar recorded a low of 0.8°C.