Delhi AQI remains ‘very poor’ as minimum temperature rises amid western disturbance

The IMD said the rise in minimum temperatures is likely to continue over the next few days, with partially cloudy skies and wind speeds of 15–20 km/hr expected on Saturday

New Delhi: Delhi’s minimum temperature rose slightly on Saturday as a western disturbance began affecting the capital, even as air quality worsened further. The city recorded a minimum of 6.8°C, three degrees below normal, after hitting 5.6°C on Friday, the lowest so far this season.

The minimum is forecast to be between 8–10°C on Sunday and Monday, according to the IMD. (Vipin Kumar/ HT Photo)

The India Meteorological Department (IMD) said the rise in minimum temperatures is likely to continue over the next few days, with partially cloudy skies and wind speeds of 15–20 km/hr expected on Saturday.

The minimum is forecast to be between 8–10°C on Sunday and Monday, according to the IMD.

Strong winds, which help disperse pollutants, are likely to improve the air quality index (AQI), which stood at 334 (very poor) at 10 am on Saturday. It was 327 (very poor) at 4 pm on Friday.

The IMD had earlier forecast isolated coldwave conditions to persist in parts of northwest India till December 5, owing to cold northwesterly winds blowing from snow-clad mountains to the plains. The minimum was 5.7°C on December 1, which was the coldest start to December since at least 2011.

However, officials said the criteria of a coldwave were not met on Friday.

The IMD classifies it as a ‘coldwave’ if the minimum temperature is below 10°C while its departure is also 4.5°C or more below normal. At least two stations need to meet this criteria on two consecutive days. On Friday, only one station – the Ridge – had a departure of more than 4.5°C below normal.

Typically, Delhi’s minimum dips below 5°C in December, but this usually happens in the second half of the month. The lowest minimum last December was 4.5°C (December 12 and 16). In 2023, it was 4.9°C (December 15). It was 5°C in 2022 (December 26); 3.2°C in 2021 (December 20); 3.1°C in 2020 (December 31); and 2.4°C in 2019 (December 28).

By this time last year, the lowest minimum had been 8°C on November 26. In 2023, it was 9.5°C on November 29, and in 2022, the lowest minimum till December 5 had been 7.6°C (December 5), data shows.

Ashwary Tiwari of IndiaMetSky said that back-to-back western disturbances were now impacting the northern plains, which will impact the minimum temperature. “Though feeble in nature, they will lead to cloudiness and this will raise the minimum temperature marginally,” he said.

Forecasts by the Centre’s Air Quality Early Warning System (EWS) for Delhi show that despite winds expected to stay strong over the weekend, the AQI is set to stay in the very poor range till at least December 8.

The Central Pollution Control Board (CPCB) classifies air as ‘good’ when AQI is 50 or lower; ‘satisfactory’ between 51 and 100; ‘moderate’ between 101 and 200; ‘poor’ between 201 and 300; ‘very poor’ between 301 and 400; and ‘severe’ when it exceeds 400.