“Cold-day” conditions were expected in parts of Delhi on Tuesday as the minimum temperature dipped to 9.6°C, three degrees above normal, and the air quality deteriorated to the “poor” category.

“Cold-day” to severe “cold-day” conditions were recorded in parts of the city on Monday as icy cold northwesterly winds prevailed in the region.

Safdarjung, which is representative of Delhi’s weather recorded a maximum temperature of 15°C, or five degrees below normal. The lowest maximum temperature on Monday of 12.8°C was recorded at West Delhi’s Pusa, as skies mostly remained overcast and grey during the day.

“Cold day” is when the maximum temperature is 4.5°C or more below normal and the minimum is below 10°C. It is a “severe cold day” when the maximum temperature is 6.5°C or more below normal and the minimum is below 10°C.

The maximum temperature of 15°C at Safdarjung and the minimum was 10.3°C met the “cold-day” criteria. The criteria were met at other stations, where the minimum was below 10°C. Pusa recorded “severe cold day conditions” with a maximum temperature of 12.8°C (eight degrees below normal), followed by Palam, where the maximum temperature was 13°C (seven degrees below normal). Ayanagar (14.2°C) and Ridge (14.9°C) recorded “cold-day” condition with maximum temperatures 5°C below normal.

“The impact of cold northwesterly winds are likely to give cold day conditions to isolated parts of Delhi on Tuesday too,” said an India Metrological Department official.

An average air quality index (AQI) of 248 (poor) was recorded at 9am on Tuesday compared to 173 (moderate) at 4pm on Monday. With an average AQI of 294, this has been Delhi’s cleanest December since AQI calculation began in 2015.