Delhi's smog season started late this year. Every November since 2018 still had Severe days

Delhi's air turned Very Poor for the first time this season on 2 November 2026, when its 24-hour AQI reached 324 (CPCB, 2 November). That is the latest first Very Poor day in at least nine years, level with 2021. In 2025 it came on 20 October. But a late start has not meant a clean November. In every November from 2018 to 2025, Delhi had between 3 and 11 Severe days, with its 24-hour AQI above 400, and in every one of those years the first Severe day had come by 13 November.

Delhi was at 350 on 3 November, under GRAP Stage 2 (CPCB, 3 November). This is what the past eight Novembers say about the weeks ahead.

Key findings

• Latest start since at least 2018. Delhi's first Very Poor day came on 2 November in 2026 and in 2021. In the other seven years it came between 15 and 24 October.
• Severe days every November. From 2018 to 2025, November had 3 to 11 days above 400 and 18 to 30 days above 300 (Very Poor or worse).
• Early, too. The first Severe day of each season came between 30 October and 13 November.
• The closest match is 2021. It also started late, after a wet October. Delhi went from 303 on 2 November to 462 on 5 November, the day after Diwali, and had 11 Severe days that month, the most of any year here.
• Rain is what made the difference in the clean Octobers, and IMD forecasts none in Delhi up to 9 November (IMD New Delhi, 3 November).

Delhi's November, year by year

All figures are Delhi's city AQI in CPCB's 4 pm bulletin, the official 24-hour average that GRAP decisions use. On India's scale, 301 to 400 is Very Poor and above 400 Severe.

Source: CPCB daily AQI bulletins, October and November of each year (2 November 2026; 5 November 2021; 11 November 2025). 2023 counts 29 November days; the bulletin for 15 November 2023 was not available. 2026 covers 1 to 3 November.

Every year had more Very Poor or worse days in November than not. In 2024 it was all 30.

Why this season started late

October 2026 was Delhi's cleanest since at least 2018, with no Very Poor day at all (our October analysis). Rain did most of the work: showers on 29 and 30 October pulled the AQI down to 60, before it climbed to 117 on 31 October, 261 on 1 November and 324 on 2 November (what rain does to Delhi's air).

2021 followed the same path. October 2021 was the second-wettest October at Safdarjung since 1961, with 122.5 mm of rain, and it too had no Very Poor day (IMD, Safdarjung October records). Then November arrived dry, Diwali fell on the 4th and stubble smoke peaked: Delhi went from 314 on 3 November to 382 on Diwali and 462 the day after.

Diwali timing matters when you compare years. In 2018, 2020, 2021 and 2023 it fell in November and pushed up those months. But November was bad in the Diwali-in-October years too: 2024 had 8 Severe days and 30 Very Poor or worse, with Diwali on 31 October.

What the next two weeks could look like

Three things set Delhi's air in early November, and two of them point up.

• Weather. IMD forecasts no rain, mainly clear skies and morning mist every day to 9 November, with light north-westerly winds of 5 to 20 km/h turning south-easterly on Diwali day (IMD New Delhi, 3 November). Light winds and cool, still nights trap smoke near the ground.
• Farm fires. Punjab had logged 1,612 farm fires by 2 November, with 98 that day (The Tribune, 2 November). North-westerly winds carry that smoke towards Delhi. Our stubble burning explainer covers why it matters.
• Diwali on 8 November. Green crackers are allowed on 7 and 8 November, from 6 to 7 am and 8 to 10 pm (The Week, 2 November). In 2021, the day after Diwali was the first Severe day of the season.

None of this guarantees a Severe day this week. IITM's air quality forecast, as reported, shows Very Poor from 3 to 5 November (India.com, 3 November). But eight Novembers out of eight had Severe days, so it is wise to plan for them. When Delhi passes 400, GRAP Stage 3 applies: most construction stops, BS-III petrol and BS-IV diesel cars are restricted and primary classes can move online (GRAP Stage 3 rules).

How we did this

• Bands. India's National AQI: 201 to 300 Poor, 301 to 400 Very Poor, above 400 Severe. "First Very Poor day" is the first day above 300 from 1 October.
• Limits. Bulletin values are city-wide 24-hour averages. Single monitors run higher: on 2 November 2026, three Delhi stations were above 400 while the city averaged 324. Station counts changed over the years (26 stations in 2018, 59 now).

For live readings, see Delhi by area and the Delhi NCR tracker.