Temperature plunges in Delhi; cold wave expected on Friday

The previous lowest minimum temperature for this season was 5.7°C on Monday, also the lowest minimum for the first week of December in at least 14 years, according to IMD data recorded from 2011 onwards.

The national capital felt the winter chill on Thursday as mercury plunged to 5.6°C at dawn, nearly 3.9°C below normal for this time of year, according to the India Meteorological Department (IMD).

The sun provided little warmth with the maximum temperature staying low, around 23.1°C (HT photo)

The previous lowest minimum temperature for this season was 5.7°C on Monday, also the lowest minimum for the first week of December in at least 14 years, according to IMD data recorded from 2011 onwards.

The sun provided little warmth with the maximum temperature staying low, around 23.1°C — about 2.2 °C below the normal for this time of December.

Met officials warned that the chill may deepen, with pockets of the city expected to face cold wave conditions with a shallow morning fog on Friday.

“Mainly clear sky can be expected with shallow fog during morning hours. Cold wave conditions at isolated places are also expected. The maximum and minimum temperatures would be around 22 and 5 degrees Celsius respectively,” said an IMD official on Thursday.

A coldwave is declared when the minimum temperature drops below 10°C, and is also 4.5°C or more below normal, with at least two stations meeting this criterion for two consecutive days.

Last week, IMD projected “normal to below-normal minimum temperatures” through winter, and as many as four to five additional coldwave days across northwest and central India — higher than is typical for Delhi in the winter.

Historical data shows Delhi rarely sees a coldwaves in early December. In recent years, the earliest coldwave in the month was recorded on December 19, 2020.

Experts attributed Thursday’s sudden dip to strong northwesterly winds following a western disturbance that moved across the Himalayas. In the coming days, officials said, colder days can be attributed to La Nina conditions that are expected to prevail over the next few months as well.

The lowest minimum recorded last year was 4.5°C on December 12 and 16; 4.9°C on December 15 in 2023; and 5°C on December 26 in 2022. In 2021, it was recorded at 3.2°C on December 20; 3.1°C on December 31in 2020; and 2.4°C on December 28 in 2019.

The all-time lowest December minimum remains 0°C, recorded on December 27, 1930. Delhi last recorded a December coldwave in 2021, with four coldwave days. Since 2011, the highest number of December coldwave days – eight – occurred in 2018.

The cold winds offered residents a brief respite from the deteriorating air quality early on Thursday, with the 24-hour rolling average air quality index (AQI) was recording at 298 in the ‘poor’ category. However, by day’s end, the AQI crept back up, slipping into the “very poor” zone and registering at 304 in Central Pollution Control Board’s 4 pm national bulletin.

Across Delhi’s 40 monitoring stations, 29 registered ‘very poor’ air, while just one at Mandir Marg recorded a marginally better AQI of 185 in the ‘poor’ category. Forecasts by the Centre’s Early Warning System for Delhi (EWS) show that AQI is likely to remain in the “very poor” category at least for the next six days.