No relief after sunset, warmest May night in 14 years

New Delhi: The city continued to reel under an intense and prolonged heatwave on Thursday, with thermal stress now at night too. The city recorded the season’s first “warm night”, a condition likely to persist in the coming days.

The minimum temperature at the city’s base station, Safdarjung, settled at 31.9°C — 5.2 degrees above normal — making it the warmest May night in Delhi in 14 years, according to IMD data. A higher minimum temperature for May -- 34.2°C -- was recorded on May 27, 2012. Delhi had last witnessed warm night conditions on April 9 and 10, 2025.

The heatwave, which began on Monday, showed no sign of receding. India Meteorological Department (IMD) has extended its heatwave alert till next Wednesday. “Heatwave conditions were observed at a few places over Delhi on Thursday, making it the fourth consecutive day. Delhi also saw warm night conditions. In this likely scenario where lower tropospheric dry northwesterly to westerly winds are prevailing in the absence of a strong western disturbance, heatwave conditions will continue to impact Delhi till May 27,” an IMD official said.

A “warm night” is when the maximum temperature exceeds 40°C in the plains and the minimum that day is 4.5 degrees or more above normal. A “heatwave” is declared when the maximum temperature crosses 40°C and is also at least 4.5 degrees above normal. The day’s conditions are also classified as a heatwave if temperatures exceed 45°C in the plains. A “severe heatwave” is declared when the maximum temperature is over 40°C and is higher than the normal by 6.5 degrees or more.

The maximum temperature at Safdarjung touched 43.6°C, 3.4 degrees above normal, while the Ridge recorded a scorching 45.3°C.

“There is a lack of western disturbance impact in the plains of northwest India, although Jammu and Kashmir experienced consistent western disturbances and fairly widespread rain. But since western disturbances don’t have sufficient amplitude, so it’s not likely to impact northwest India. So the heatwave will continue to impact the city. Red to orange alerts have been issued for Punjab, Haryana, Delhi, north Rajashtan and MP and south UP,” said IMD scientist Krishna Mishra.

An orange alert for heatwave conditions has been sounded for Delhi till May 27, while warm night conditions are expected again on Friday.

Last May, Delhi’s highest maximum temperature was 42.3°C and the city recorded no heatwave days. In contrast, 2024 saw six consecutive heatwave days, with the mercury peaking at 46.8°C on May 30. On the same day, stations such as Narela and Mungeshpur crossed 49°C.

Delhi’s air quality slipped back into the poor zone. The AQI stood at 209 at 4 pm on Thursday, up from 168 on Wednesday.