January 2025 was Delhi’s hottest since 2019

Delhi experienced its hottest January day since 2019, with temperatures reaching 27°C, impacting air quality positively despite a 'very poor' AQI.

It was a fairly warm end to January on Friday as the maximum temperature touched 27°C, five degrees above normal, making it the hottest January day in Delhi since January 21, 2019, when it was 28.7°C. A sunny and hot end to the month has clocked the monthly average maximum temperature at 21.1°C — a degree above the long period average (LPA) of 20.1°C, also making it the warmest January since 2019, when the average maximum was 21.2°C.

Commuters out on a cold foggy morning near Akshardham Temple on NH 24 on Friday. (Sanjeev Verma/HT Photo)

India Meteorological Department (IMD) data showed nights were also a degree warmer, with the average monthly minimum clocked at 8.5°C, a degree above the LPA of 7.5°C. This was Delhi’s highest average minimum since 2017, when it was 8.7°C, data showed.

Experts said that while a number of western disturbances were seen in northwest India, most were feeble, thus not bringing substantial snowfall or rain this month.

“Even if we had one or two strong western disturbances, we would have had good rain in the plains and adequate snowfall in the mountains. This leads to icy-cold winds blowing and also cloudiness in the region, which translates to that winter chill. This January, we have seen cloudiness and scattered drizzle, but no proper winter rain or snowfall, which has meant temperature has risen fairly early and quickly too,” Palawat said, adding northwest India was deficient by around 81% this month in terms of rainfall.

He added lack of rain also contributed to reduced fog. “In January, dense to very dense fog is common, but particularly in the second half of the month it has been almost missing,” he added.

Delhi’s minimum temperature on Friday was 9.5°C, which was a degree above normal. It was 9.2°C a day earlier. IMD has forecast warm easterly winds with the minimum likely to hover between 10-12°C over the weekend.

The lowest minimum this month was 5.6°C on January 28. The lowest maximum was was 15°C on the first day of the month.

Higher temperatures have helped Delhi’s air quality, which has been comparatively cleaner as compared to previous years. Delhi’s average air quality index (AQI) was 305 for the month, making it the lowest for January since 2022 when it was 279. Lower temperatures negatively impact air quality, slowing down dispersion of pollutants and bringing down the mixing height.

The average AQI in January 2024 was 355 and it was 311 in 2023.

AQI on Friday was 351 (very poor). “Delhi’s air quality is likely to be in the ‘very poor’ category from February 1 till February 3. The air quality is likely to be in the ‘very poor’ to ‘poor’ category in the subsequent six days,” said the Centre’s Early Warning System for Delhi in its daily bulletin.