Wind change brings humidity, Delhi sweats with mercury at 44°C

Delhi continues to face torrid temperatures, with a maximum of 44°C, just shy of a heatwave. IMD predicts isolated thunderstorms and light rain.

Mercury continued to remain in the torrid zone in Delhi for the 12th consecutive day on Tuesday, which was aggravated by strong southwesterly winds that brought humidity into the fore, according to data from the India Meteorological Department (IMD).

People cover their heads to stave off the heat on Wednesday. The Met department has predicted isolated thunderstorms and drizzle in Delhi and NCR for Thursday. (Sunil Ghosh/HT photo)

As the heat refused to abate, the maximum rose marginally and was recorded at 44°C — four degrees above normal, and 0.5 degrees shy of being officially declared a “heatwave” condition — at Safdarjung, representative of Delhi’s weather. The maximum was 43.8°C a day earlier. The southwesterlies prevailed during the day and a wind speed of 30-40 km/hour was recorded in some places even as relative humidity remained moderate.

Delhi’s minimum was 31°C, three degrees above normal and the highest minimum for June in two years. It was last higher on June 14, 2022 (31.2°C).

IMD said the impact of a western disturbance, along with southwesterly winds, will likely retain moisture in the atmosphere. The weather agency has predicted isolated thunderstorms and light rain for Thursday. Two weather stations, Ridge and Ayanagar, received “trace” rainfall in the early hours of Wednesday.

“We can expect similar weather to continue over the next few days with hot days but there are chances of an isolated dust storm and drizzle towards the evening and night,” said an IMD official, adding there is an orange alert in place for Thursday.

The highest maximum in Delhi was 46.4°C at Najafgarh in southwest Delhi. According to IMD, it is considered a heatwave day when the maximum temperature is over 40°C, while also being 4.5 degrees or more above normal. Parts of Delhi have been recording heatwave conditions since May 25.

Delhi’s relative humidity oscillated between 21% and 52% on Wednesday. It was between 26% and 64% on Tuesday. This slight drop in relative humidity meant Delhi’s Heat Index (HI) or “real feel” also dropped to 46°C compared to 48.6°C a day earlier.

Delhi’s wet bulb temperature, another indicator of the comfort level, was between 25.1°C and 25.7°C. The highest wet bulb value was 27.1°C a day earlier. A wet bulb temperature of 32°C or higher makes it difficult for people to be outdoors for long and at 35°C — the maximum threshold — humans can no longer regulate body temperatures, leading to heat strokes and potential collapse.

In Delhi, this tends to be over 30°C, usually in July and early August, when temperatures are high and there is moisture intrusion, due to the southwest monsoon.

IMD has forecast Delhi’s maximum to dip by around two degrees, set to hover around the 42°C mark at Safdarjung on Thursday. However, humidity will continue to remain high, the weather agency said.