Delhi’s average daily high in May came to 39.7 degrees Celsius, and the average low to 25.8. Only one May in recent years was hotter: 2024, when the averages were 41.7 and 26.5 degrees Celsius.
So the month counts as the capital’s hottest May in two years. It was also, oddly, the cleanest in about five.
Cool start, brutal middle
The heat did not build steadily. Experts said frequent western disturbances brought early pre-monsoon activity and held temperatures down through the first half of May. Once those systems weakened, the mercury jumped. A heatwave ran from May 18 to 21, and maximum temperatures passed 46 degrees Celsius in some parts of the city.
Nights were hot too. The India Meteorological Department (IMD) recorded minimums of 32.8 degrees Celsius on May 26 and 31.9 degrees Celsius on May 21, among the highest nighttime readings in Delhi in 14 years.
Mahesh Palawat of Skymet Weather blamed a mix of western disturbances, induced cyclonic circulations over Rajasthan and nearby areas, and moisture-laden winds from the Bay of Bengal. Late in the month, he said, thunderstorms, rain and gusty winds picked up across the capital and gave relief from the heat in the last few days. Delhi got 17.61 mm of rain over the month.
For reference, the IMD calls it a heatwave when the maximum temperature exceeds 40 degrees Celsius and sits 4.5 to 6.4 degrees Celsius above normal.
The air got better anyway
An analysis by the Centre for Research on Energy and Clean Air (CREA) put the city’s average AQI at 161 through May 29. That is the lowest for the month since 2021, when it was 144. May 2025 averaged 170 and May 2024 averaged 223.
Day by day, from May 1 to May 29, Delhi logged three satisfactory days, 20 moderate days and six poor days. None were very poor or severe. May 2021 had six satisfactory days, 22 moderate and three poor.
On Saturday, May 30, after widespread rain and strong winds, the AQI came in at 85, rated satisfactory. It was the cleanest day of any May since 2023 and the fourth satisfactory day this month.
Experts said rain and intermittent strong winds scattered the pollutants. Dust blown in from Rajasthan set off several dust storms and hurt air quality at times, but intense local rainfall washed particulate matter out of the air.
Palawat expects no heatwave in the first week of June. Temperatures should creep up from June 1 as the current rainy spell weakens and moves away from the region.
Sources
- Hottest in two years, cleanest air in five: Delhi's May of extremes
- Scorching heat, cleaner air: Delhiâs May weather swings between extremes
Sources
- Hottest in two years, cleanest air in five: Delhi's May of extremes
- Scorching heat, cleaner air: Delhi's May weather swings between …
