New Delhi continues to suffer under an intense and prolonged heatwave, with thermal stress now extending into the night. The city recorded its first "warm night" of the season on Thursday, a condition likely to persist in the coming days.
Record-Breaking Night Temperatures
The minimum temperature at the city's base station, Safdarjung, settled at 31.9 degrees Celsius, which is 5.2 degrees above normal. This marks the warmest May night in Delhi in 14 years, according to the India Meteorological Department (IMD). A higher minimum temperature for May, 34.2 degrees Celsius, was recorded on May 27, 2012. Delhi had last experienced warm night conditions on April 9 and 10, 2025.
Heatwave Alert Extended
The heatwave, which began on Monday, shows no signs of abating. The IMD has extended its heatwave alert until 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.
Understanding Warm Night and Heatwave Criteria
A "warm night" is defined when the maximum temperature exceeds 40 degrees Celsius 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 degrees Celsius and is at least 4.5 degrees above normal. The day's conditions are also classified as a heatwave if temperatures exceed 45 degrees Celsius in the plains. A "severe heatwave" is declared when the maximum temperature is over 40 degrees Celsius and is higher than normal by 6.5 degrees or more.
Daytime Temperatures Soar
The maximum temperature at Safdarjung touched 43.6 degrees Celsius, 3.4 degrees above normal, while the Ridge recorded a scorching 45.3 degrees Celsius.
"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, 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 Rajasthan, Madhya Pradesh, and south Uttar Pradesh," said IMD scientist Krishna Mishra.
Orange Alert Issued
An orange alert for heatwave conditions has been sounded for Delhi until May 27, while warm night conditions are expected again on Friday.
Comparison with Previous Years
Last May, Delhi's highest maximum temperature was 42.3 degrees Celsius, and the city recorded no heatwave days. In contrast, 2024 saw six consecutive heatwave days, with the mercury peaking at 46.8 degrees Celsius on May 30. On the same day, stations such as Narela and Mungeshpur crossed 49 degrees Celsius.
Air Quality Deteriorates
Delhi's air quality slipped back into the poor zone. The Air Quality Index (AQI) stood at 209 at 4 pm on Thursday, up from 168 on Wednesday.
