Delhi logs hottest day in 2 years, max crosses 45°C

Mercury surged in the Capital on Sunday to mark a record-high maximum temperature of 45.4°C, the highest this season so far and five degrees above normal — making for an uncomfortably hot daytime — according to data from the India Meteorological Department (IMD).

The torrid temperatures led to “heatwave” to “severe heatwave” conditions for the second consecutive day in Delhi, which recorded its hottest day in two years. The previous high was 45.6°C on May 16, 2022. Though Safdarjung, representative of Delhi’s weather, recorded 45.4°C, matters were worse at other stations with some even crossing the 48-degree threshold for the first time this season. At Mungeshpur, it was 48.3°C and at Najafgarh 48.1°C, IMD said.

This was also the first day this season when Safdarjung recorded a heatwave. Until now, only other weather stations in Delhi had been recording heatwave to severe heatwave conditions.

No immediate relief is in sight, the Met said, issuing a “red alert” for severe weather conditions till Thursday. These conditions are largely down to the westerly winds returning to the region.

“The westerlies on Saturday led to a sharp rise in temperature again. These extremely hot winds, that blow from Rajasthan, combined with clear skies, is leading to such extreme conditions,” said Kuldeep Srivastava, scientist at IMD, adding that a marginal drop in temperature is only likely on May 31, when a western disturbance might bring cloud cover.

Despite the high temperature, Delhi’s heat index (HI) or “real feel” was only around 49°C, a degree higher than Saturday’s 48°C. This too was down to the drier westerlies that have replaced the humid heat that prevailed on Tuesday. The HI at the time was 55.4°C. HI takes into account relative humidity and air temperature — a phenomenon that makes it difficult to sweat and leads to potential health crises in the process.

Delhi’s wet bulb temperature, another indicator of how uncomfortable it is outside, was recorded at 26.1°C. It was 28.3°C a day earlier. A wet-bulb temperature of 32°C or higher makes it difficult for people to work outdoors for too long. If the wet-bulb reading is 35°C, the maximum threshold, humans can no longer regulate body temperatures, leading to heatstroke and potential collapse.

Though temperatures seared through the day, the morning was much cooler. The minimum temperature was 27°C, which was around normal for this time of the year. The minimum is forecast to rise again and may touch 30°C by Friday, IMD added.

IMD classifies it as a “heatwave” when the maximum temperature is 4.5°C above normal and also above 40°C. It is a “severe heatwave” when the maximum is 6.5°C or more above normal.

For Safdarjung, the highest maximum before Sunday was 44.4°C, on May 19. On the same day, Najafgarh touched 47.8°C, the highest for any weather station in Delhi this season. “Sunday’s heat has seen two stations in Delhi cross 48°C for the first time this year. There are chances the maximum may hover in this range for the next two to three days,” said an IMD official.

Parts of Delhi-NCR reeled under four consecutive heatwave to severe heatwave days between May 17 and 20. From May 21, moist easterly winds led to a drop in temperature and heatwave conditions abated. This second spell of heatwave in Delhi-NCR began on May 25.