Delhi has recorded its lowest October average air quality in eight years. According to the Union Environment Ministry, the national capital’s average Air Quality Index (AQI) for October 2026 stood at 166, the lowest for the month since 2018, with more days in the ‘Good to Moderate’ categories than in most previous years.
For one month at least, Delhi’s air told a different story from the one residents have come to expect in October.
Key Takeaways
- Delhi’s October 2026 average AQI was 166, its lowest October reading in eight years, according to the Union Environment Ministry.
- Between January and October 2026, the capital recorded 220 days in the ‘Good to Moderate’ air quality category.
- Exceptional rain helped clear the air, but forecasts warn air quality could deteriorate to ‘poor’ from November 1.
What the official figures show
The ministry’s statement put the October monthly average at 166, down from 223 in October 2025 and 234 in 2024. The earlier figures in the same series were 219 in 2023, 210 in 2022, 173 in 2021, 265 in 2020, 234 in 2019 and 269 in 2018.
The improvement was not limited to a single month. Delhi’s average AQI for the January to October period in 2026 stood at 167, compared with 170 in 2025, 184 in 2024, 172 in 2023, 187 in 2022, 179 in 2021, 156 in 2020, 192 in 2019 and 201 in 2018. During January to October 2026, the capital recorded 220 days in the ‘Good to Moderate’ category, defined as a daily average AQI below 200.
A separate analysis by the Centre for Research on Energy and Clean Air (CREA) put the October average slightly differently, at 167, and described it as the lowest for October since 2015. The two readings point in the same direction even though the headline numbers differ by a single point, and both series show a clear improvement on the Octobers of the last few years.
For one month at least, Delhi’s air told a different story from the one residents have come to expect in October.
Rain did much of the heavy lifting
Weather played a major part in the cleaner month. Delhi received 123.3 mm of rainfall up to the morning of Friday, October 30, more than eight times its October normal of 15.1 mm, according to reports citing CREA’s analysis. Friday alone brought 61.4 mm of rain in 24 hours, making it the wettest October day in four years.
As the rain fell, the daily AQI dropped to 60 on Friday, the cleanest October day since October 10, 2022, when it stood at 44. The month’s highest AQI reading was 245, the lowest monthly peak since 2015. Across the month, Delhi recorded five ‘poor’ days, three ‘satisfactory’ days and 22 ‘moderate’ days, and it entered the ‘poor’ category on October 21, the first time since 2015 that this happened in the second half of October.
The same wet spell that washed the air also brought an unusual chill. The maximum temperature on Friday was 20.7 degrees Celsius at Safdarjung, the city’s base weather station, 10.3 degrees below the seasonal average and the lowest October daytime temperature recorded there since 1951. The city had already made headlines this month for a rain-soaked Delhi weekend, and analysts noted that the AQI was already relatively low before the Graded Response Action Plan (GRAP) was imposed, falling further as the heavy rain arrived.
- October average AQI: 166 (ministry figure), the lowest October reading in eight years
- January–October average AQI: 167, with 220 ‘Good to Moderate’ days
- October rainfall: 123.3 mm, more than eight times the month’s normal of 15.1 mm
- Cleanest October day: AQI 60 on October 30, the best since October 2022
- Wettest October day in four years: 61.4 mm of rain on Friday, October 30
What it does not mean yet
The ministry said the Commission for Air Quality Management (CAQM) is working with stakeholders to prevent, control and reduce air pollution across Delhi-NCR, and pledged intensified efforts for the region. Policy choices around the winter months remain closely watched, including the question of firecrackers: the Supreme Court declined a complete firecracker ban in Delhi-NCR earlier this month.
There is also a warning attached to the good news. The Air Quality Early Warning System has forecast that Delhi’s air quality will remain in the ‘moderate’ category on Saturday before deteriorating to ‘poor’ on November 1, with the outlook for the following six days suggesting pollution levels could remain in the ‘poor’ and ‘very poor’ categories. In other words, October’s clean air may prove to be a weather-assisted pause rather than a permanent change, and the real test will come as winter sets in and the rain stops.
What to Watch Next
Watch whether the forecast deterioration to ‘poor’ from November 1 materialises, whether the CAQM’s intensified efforts for Delhi-NCR hold pollution in check as winter arrives, and whether the January to October improvement — 220 ‘Good to Moderate’ days so far — survives the months when Delhi’s air has traditionally been at its worst.