Delhi recorded its first citywide heatwave of the season on Saturday, with the base station at Safdarjung logging a maximum of 42.8°C — 5.1 degrees above normal — as four of five key weather stations simultaneously satisfied the India Meteorological Department’s (IMD) dual criteria for a formal declaration.
The reading is the highest April maximum at Safdarjung in four years. In April 2022, the station had recorded 43.5°C across late April.
IMD classifies a heatwave when the maximum temperature exceeds 40°C and is at least 4.5°C above normal, or when it touches 45°C regardless of departure.
A citywide declaration for Delhi requires at least two stations to meet the criteria, including Safdarjung as the base observatory. On Saturday, four of the five stations monitored met the thresholds. The Ridge station recorded the city’s highest maximum at 44.5°C, 6.1 degrees above normal. Lodhi Road registered 42.6°C (5.6 degrees above normal) and Ayanagar 43.2°C (4.8 degrees above normal). Palam recorded 42.5°C.
IMD issued a yellow alert for Sunday, warning of heatwave conditions, with a possible shift towards thunderstorm activity from April 27 onwards.
On Saturday, IMD confirmed that heatwave conditions had prevailed across the Delhi region for three consecutive days — though the department had not communicated this formally until Friday, despite queries on Thursday. “Heat wave conditions have been realised at many places over Delhi. This is the third consecutive day of heat wave realisation over Delhi region. These conditions are likely to continue till Sunday. Under the influence of setting in of lower tropospheric level easterly winds, maximum temperatures are likely to fall leading to abatement of heat wave conditions over the region from April 28,” an IMD official said.
Minimum temperatures also remained elevated. Safdarjung recorded 25.2°C, 2.5 degrees above normal; Palam logged 26.8°C, 3.5 degrees above normal. No rainfall was recorded at any station in the 24-hour period ending 5:30 pm on Saturday, sustaining the heat build-up.
The conditions are being driven by dry northwesterly winds and strong solar heating, typical contributors to early-season heatwaves in northwest India.
April heatwaves are not unusual for the capital. Delhi recorded three heatwave days between April 7 and 9 last year. April 2022 saw 11 such days; April 2017 recorded four and April 2016 one.
Mahesh Palawat, vice chairman at Skymet Weather, said: “No relief is likely until chances of some rainfall across northwest India from April 26 to 28. There could be a slight cooling effect. This is likely because of a cyclonic circulation developing over Rajasthan, with chances of rain over Punjab, Haryana and Delhi, among other places in northwest India.”
IMD has indicated a similar outlook, attributing the expected change to a shift in lower tropospheric wind patterns. Easterly winds — which carry relatively more moisture than the prevailing dry westerlies — are forecast to influence conditions from April 27, potentially triggering isolated thunderstorm activity and a marginal dip in maximum temperatures.
Sunday may still see heatwave or near-heatwave conditions before a gradual moderation sets in. Daytime temperatures could fall by 2–4 degrees Celsius between April 27 and 28, depending on cloud cover and precipitation. “Partly cloudy sky with possibility of thundery development with a spell of very light rain towards afternoon is expected on Monday. Sustained surface winds speed 30-40 kmph gusting to 50 kmph is also expected during the day,” IMD bulletin stated. Similar conditions are expected to persist till April 29.
The anticipated rainfall is likely to be scattered rather than widespread, accompanied by gusty winds and lightning — pre-monsoon thunderstorm activity typical of the transition between peak summer heating and the early build-up of monsoon circulation. Beyond the immediate forecast window, temperatures are expected to remain above normal even if heatwave conditions abate temporarily.
Delhi’s air quality deteriorated alongside the heat. The air quality index stood at 243 on Saturday, up from 226 on Friday, with both readings in the “poor” category per the Central Pollution Control Board’s daily bulletin. The Centre’s Air Quality Early Warning System has forecast AQI to remain poor through Sunday.