According to the IMD norms, a heatwave is declared when the maximum temperature is greater than or equal to 45°C, or when it is 4.5°C to 6.4°C above normal. (Express Photo By Amit Mehra)Delhi continued to simmer on Wednesday as the maximum temperature settled at 43.3 degrees Celsius while the India Meteorological Department (IMD) indicated a “feel-like” or heat index value of over 51.9°C by the evening, said officials. Meanwhile, a red alert has been sounded for heatwave conditions in the Capital, warning of severe discomfort through Thursday. Relief is likely over the weekend.However, senior IMD officials also clarified, India does not officially validate or maintain records of the heat index, which is calculated based on a combination of temperature and humidity. “Heat index depends on temperature and relative humidity and varies throughout the day. However, it is not validated under Indian conditions, and no formal records are maintained,” a senior official said.A yellow alert has been sounded for Friday, with conditions expected to ease from June 14 amid the possibility of rain. The maximum temperature is likely to range between 43°C and 45°C until Friday, the Met Office said.At Delhi’s Safdarjung observatory, the city’s base weather station, the maximum temperature climbed to 43.3°C, which is 3.4°C above normal on Thursday. The minimum temperature settled at 27.2°C, nearly a notch below normal.At 45°C, the Ayanagar weather station logged Delhi’s highest temperatures since mid-May on Wednesday, 3.5°C above normal, as it met IMD’s official threshold for heatwave classification. By contrast, Lodhi Road has consistently recorded the lowest daytime highs among city stations during the same period.According to the IMD norms, a heatwave is declared when the maximum temperature is greater than or equal to 45°C, or when it is 4.5°C to 6.4°C above normal. If it crosses this range, it qualifies as a severe heatwave. A hot summer day, in New Delhi, Wednesday, June 11, (Express Photo By Amit Mehra)“From yesterday’s three stations reporting heatwave conditions, today only Ayanagar has reported a heatwave. Temperatures are likely to remain in the same range tomorrow and are expected to see a gradual decline from June 13,” said an IMD official.Story continues below this adWhile there was a slight drop in daytime temperatures across the National Capital Region (NCR) over the past 24 hours, the night temperatures also showed a decline and were below or near normal.In recent days, the Capital has also faced hot and humid conditions, another form of heat stress. The IMD sounds alerts for such conditions when daytime temperatures are three degrees above normal and relative humidity levels are significantly high.On Wednesday, the humidity during the day fluctuated between 31% and 73%, and north-westerly winds blew at speeds of up to 18 kmph, according to IMD’s daily weather bulletin.“Heatwave conditions were observed in parts of West Rajasthan, Punjab, Jammu & Kashmir, Himachal Pradesh, south Haryana-Delhi, and isolated pockets of East Rajasthan and south Uttar Pradesh. Severe heatwaves were reported at isolated locations in West Rajasthan, Punjab, and Jammu & Kashmir,” the IMD said.Story continues below this adTemperatures dropped slightly — up to 2°C— in parts of north Haryana, Uttarakhand, and northwest Uttar Pradesh, while Chandigarh and Patiala remained above heatwave thresholds. In the rest of northwest India, temperatures rose by around 1°C, with Ganganagar (Rajasthan) registering 48°C, the highest maximum temperature in the country this season.Stay updated with the latest - Click here to follow us on Instagram© The Indian Express Pvt LtdTags:Delhi weatherDelhi weather today