New Delhi: The weather in Delhi was at its peak in the month of May, May was the hottest in two years, while the air quality this month was also recorded as the cleanest in almost five years.According to the data, the average maximum temperature of the city in May was 39.7 degrees Celsius, while the average minimum temperature was 25.8 degrees Celsius. The last warmest May was in 2024, when the average maximum and minimum temperatures reached 41.7 °C and 26.5 °C, respectively.The weather patterns kept changing in the capital throughout the month. Experts said frequent western disturbances and associated weather systems triggered pre-monsoon activity, leading to low temperatures during the first half of May. As these systems weakened, temperatures rose rapidly and heat wave conditions developed in parts of Delhi before another round of strong pre-monsoon activity returned towards the end of the month.As quoted by PTI, Skymet Weather’s Mahesh Palawat attributed the month’s fluctuating weather to a combination of western disturbances and cyclonic circulation induced over Rajasthan and adjoining areas and moisture-laden winds from the Bay of Bengal.Heat wave conditions were recorded between 18 and 21 May, with maximum temperatures crossing 46 degrees Celsius in some parts of the city.Nights in Delhi also remained unusually hot, with the minimum temperature reaching 32.8 degrees Celsius on May 26 and 31.9 degrees Celsius on May 21, among the highest night temperatures recorded in the city in the last 14 years, according to the India Meteorological Department (IMD).The IMD defines heatwave as a situation where the maximum temperature exceeds 40 degrees Celsius and is 4.5 to 6.4 degrees Celsius above normal.A hot night is declared when the maximum temperature is 40 degrees Celsius or more and the minimum temperature is also 4.5 to 6.4 degrees Celsius above normal.Delhi received 17.61 mm rainfall during the month. Palawat noted that thunderstorms, rain and strong winds intensified in late May, causing widespread weather activity across the capital and providing relief from the scorching heat of the past few days.Rain and strong winds also helped improve the air quality. Despite high temperatures, Delhi recorded the cleanest air quality in May in nearly five years.An analysis by the Center for Research on Energy and Clean Air (CREA) showed that the capital’s average AQI as of May 29 was 161, the lowest for the month since 2021, when it was 144.Experts said rain and intermittent strong winds played a significant role in spreading the pollutants. While the dust brought from Rajasthan gave rise to several dust storm events and affected the air quality, local intense rainfall helped flush out particulate matter and improve the overall air quality across the city.The data showed that between May 1 and May 29, Delhi recorded three satisfactory days, 20 moderate days and six poor days, with no very poor or severe air quality days. In comparison, May 2021 recorded six satisfactory days, 22 moderate days and three poor days, with the average AQI at 144. The average AQI was 170 in May 2025 and 223 in May 2024.On May 30, Delhi recorded a satisfactory AQI of 85 after widespread rainfall and strong winds. This was the cleanest air quality day in May since 2023 and the fourth satisfactory air quality day this month.Looking ahead, Palawat said no heat wave conditions are expected during the first week of June. However, temperatures are expected to rise gradually from June 1 as the current spell of rain activity will weaken and move away from the region.