Rainfall lowers Delhi's AQI to 78 and brings cooler temperatures
Heavy rain on Friday reduced Delhi's air-quality index from 363 to 78 and caused temperatures to fall, with the city recording its coldest October daytime high in four years.
Heavy rainfall on Friday caused Delhi's air-quality index (AQI) to drop from 363 on Thursday morning to 78 on Friday morning, moving the city from the severe pollution range to the satisfactory category, according to data from AQI.in. The downpour also brought cooler weather, with the Safdarjung weather station recording a daytime high of 25.4 °C, the lowest October daytime temperature in four years, and nighttime lows between 15 °C and 18 °C.
India Meteorological Department (IMD) data showed that Safdarjung received 61.4 mm of rain in the 24-hour period ending Friday morning, the wettest October day in the city in four years. The department attributed the event to a combination of a western disturbance over the Western Himalayas, an induced cyclonic circulation over South Punjab, and winds from the Bay of Bengal carrying remnants of Cyclone Arnab.
"The rainfall over Northwest India, including Delhi, Punjab, Haryana, East Rajasthan, and parts of Uttar Pradesh, can be attributed to a western disturbance over the Western Himalayas and an induced cyclonic circulation over South Punjab. Moreover, winds from the Bay of Bengal, driven by the remnants of Cyclone Arnab, were also reaching up to Delhi," said Mahesh Palawat, Vice President of Meteorology and Climate Change at Skymet Weather Services.
Palawat added that the convergence of these systems produced unseasonal rain, noting that such heavy rainfall (50-60 mm) is unusual for the region in October.
The IMD forecast predicts partly cloudy skies on October 31 and November 1, with temperatures expected to rise gradually to the 28 °C-31 °C range in early November. Across India, the agency expects varied weather, including heavy rain in parts of South Peninsular India, scattered showers in Central India, and light rain in the eastern and northeastern states.
Experts caution that the improvement in air quality may be short-lived. Palawat warned that as the sun returns and temperatures rise, pollution levels could increase again, potentially reaching poorer categories by mid-November as Diwali approaches.