At 8.7°C, chill tightens grip on Delhi, air still ‘very poor’

Delhi recorded a minimum temperature of 8.7°C, the lowest for November since 2022, with "very poor" air quality expected to persist.

The city continued to feel the chill on Monday as the minimum temperature was recorded at 8.7 degrees Celsius (°C), four notches down from the season’s normal temperature. It was also the lowest minimum for November, since 2022, when it was 8.3°C on November 30.

The 24-hour average AQI was logged at 351 on Monday. (Arvind Yadav/HT Photo)

The minimum is likely to oscillate between 9-11°C till Thursday, as per the India Meteorological Department (IMD).

A return of easterly winds is likely to raise the minimum above 11°C on November 21, the IMD said. Despite the dip in mercury, a “coldwave” was not declared in the region on Monday as none of the weather stations met the criteria.

The IMD classifies it as a “coldwave” if the minimum temperature is below 10°C while the departure from normal is 4.5°C or more. At least two stations need to meet this criteria on two consecutive days.

The maximum temperature was recorded at 27.1°Con Monday.

Mahesh Palawat, vice president at Skymet said the current dip in temperature at nighttime is due to cold northwesterly winds and clear skies, leading to radiational cooling – a phenomenon when heat is lost quickly at nighttime as there are no clouds to obstruct or trap it. “There will be a gradual dip in the coming days, but a coldwave is unlikely. For a coldwave to happen, the minimum would have to dip below 7°C,” said Palawat, adding that no significant western disturbance is expected till the end of the month.

Though dipping temperature negatively impacts the air quality index (AQI), Delhi has been helped by an increase in wind speed and a change in wind direction – marginally reducing the share of stubble smoke in Delhi’s air. The IMD said consistent winds of 10km/hr prevailed in the city on Sunday, with the wind direction predominantly westerly as compared to northwesterly.

The Capital saw “very poor” air for the fourth straight day on Monday. The 24-hour average AQI was logged at 351, as against 377 on Sunday and it is likely to remain “very poor” atleast till Thursday.

“Delhi’s air quality is likely to be in the ‘very poor’ category from November 18 till November 20,” said the Early Warning System (EWS) – a forecasting model under the Ministry of Earth Sciences (MoES).

Stage 3 measures of the Graded Response Action Plan (Grap) were enforced in Delhi on November 11.

Data from the Centre’s Decision Support System (DSS) showed the contribution of stubble burning in Delhi’s total PM 2.5 was 16.47% on Saturday, but dipped to around 12.8% on Sunday. DSS did not share the actual contribution of stubble burning on Monday.

Data by the Central Pollution Control Board (CPCB) on Monday showed that out of Delhi’s 39 active ambient air quality stations, three were in the “severe” category. Wazirpur, with an AQI of 409, was the worst impacted, followed by Bawana (408) and Alipur (401).

HT on November 17 reported how Delhi’s average AQI for the period November 1-15 – considered as the most polluted period in the entire year – stood at 349, marginally lower than 367 in 2024 and 376 in 2023, and only slightly higher than the 345 recorded in 2022.

Experts said a delayed harvest season, fewer farm fires so far and an early Diwali have all helped keep the numbers from sliding further towards the “severe” zone. Data anomalies and missing data across the 39 active ambient air quality monitoring stations are likely to have played a part, they had said.