Delhi wakes up to fog in summers, records lowest minimum temperature since May 2009

Thursday morning’s minimum of 15.8 degrees Celsius is fairly close to the all-time May record of 15.2 degrees, which was recorded on 2 May 1982

Delhi NCR witnessed unusually dense fog in the early hours of Thursday, with the Safdarjung weather station recording a minimum temperature of 15.8 degrees Celsius, nine degrees below normal for this time of the year.

Foggy conditions in Delhi NCR on Thursday morning. (Sunil Ghosh/ HT Photo)

This is also the lowest minimum temperature for May since at least 2009, according to data available with the India Meteorological Department (IMD). Safdarjung is the base station for Delhi’s weather conditions.

While Palam experienced shallow fog with a visibility limit of 800 metre, it fell to as low as 100 metre in Safdarjung. The IMD classifies fog as ‘shallow’ when visibility is between 500 and 1,000 metre, ‘moderate’ when visibility is between 200 and 500 metre, and ‘dense’ when it is below 200 metre. It is ‘very dense’ when visibility is below 50 metre.

IMD scientist Kuldeep Srivastava said the dense fog conditions lasted for around two hours, with a visibility of around 200 metre at 7.30 am. He attributed this phenomenon to a combination of high moisture content and calm winds.

“It is surprising to see fog at this time of the year, which is because of the high moisture content in the air following Wednesday’s rain. Winds were almost calm at night, and this led to a gradual build-up of fog, which then impacted the minimum temperature,” Srivastava said.

Thursday morning’s minimum of 15.8 degrees Celsius is Delhi’s lowest for this month in 41 years when it was 15.2 degrees on 2 May 1982. The all-time record for May is 15.1 degrees, recorded on 2 May 1969. Last year, the lowest minimum was 17.2 degrees (May 23), while it was 18 degrees in 2021 (May 22). Delhi’s minimum on Wednesday was 20.1 degrees, which too was five degrees below normal.

The IMD has forecast drizzles in some parts of the national capital region today, but the sun is expected to be out for large parts of the day in most places. “Due to the gradual rise in temperature and high moisture, we will see localised rainfall in some places. But it will largely be a sunny day,” Srivastava added, forecasting the maximum to touch around 32 degrees Celsius through the day vis-a-vis 30.6 degrees on Wednesday, which was nine degrees below normal.

Delhi’s minimum temperature is expected to stay between 18-20 degrees Celsius till May 10.

Meanwhile, Delhi’s air quality index (AQI) was in the satisfactory range. The 24-hour average AQI stood at 88 at 9 am, compared to 103 (moderate) at 4 pm on Wednesday, according to the Central Pollution Control Board (CPCB).

Forecasts show the AQI is likely to return to the ‘moderate’ category later today and will remain so till Saturday.

The CPCB classifies AQI between 0-50 as ‘good’, between 51 and 100 as ‘satisfactory’, between 101 and 200 as ‘moderate’, between 201 and 300 as ‘poor’, between 301 and 400 as ‘very poor’ and over 400 as ‘severe’.