Delhi AQI Winter 2026-27 Starts Cleaner Than the Last 3 Winters

Delhi’s average AQI over the first 17 days of October 2026 was 152, the lowest for that stretch in any of the last four years, and the city has not had a single “Poor” day yet. By the same date in 2023, 2024 and 2025 it had logged 7, 4 and 4 Poor days. That is based on all 68 of CPCB’s official daily bulletins for 1 to 17 October in each year. The caveat matters as much as the number: winter has barely started, and Delhi’s worst air has always arrived in November.

1 to 17 October: 2026 against the last three years

	2023	2024	2025	2026
Average AQI, 1 to 17 Oct	188	177	157	152
Average, 1 to 6 Oct	169	160	124	177
Average, 7 to 17 Oct	199	187	175	139
Poor days (AQI above 200)	7	4	4	0
Satisfactory days (100 or below)	1	0	4	2
Worst day	257 (14 Oct)	285 (17 Oct)	254 (17 Oct)	187 (4 Oct)
First Poor day	6 Oct	13 Oct	14 Oct	Not yet

The shape of the month is the real story. In each of the last three years, Delhi’s air got worse as October went on: the average rose from 169 to 199 between the first six days and the next eleven in 2023, from 160 to 187 in 2024, and from 124 to 175 in 2025. This year it went the other way, from 177 to 139. October 2026 actually started worse than any of the three earlier years, which is why early reports called it the most polluted start to October in four years. Then it cleaned up, including a Satisfactory reading of 83 on 12 October.

That also means GRAP Stage I, the first tier of Delhi-NCR’s emergency pollution plan, which is meant for AQI between 201 and 300, has had no day in that range to respond to on the CPCB 4 PM bulletin. In 2024 and 2025 Stage I came in around 14 to 15 October, right after the first Poor days in our table.

Day by day

Date	2023	2024	2025	2026
1 Oct	147	151	130	166
2 Oct	146	174	123	174
3 Oct	155	162	88	171
4 Oct	176	183	138	187
5 Oct	177	145	159	184
6 Oct	212	143	105	179
7 Oct	216	126	73	136
8 Oct	164	167	81	162
9 Oct	175	164	100	176
10 Oct	180	132	170	122
11 Oct	193	141	199	111
12 Oct	220	155	167	83
13 Oct	256	224	189	158
14 Oct	257	234	211	181
15 Oct	233	198	233	149
16 Oct	207	230	245	90
17 Oct	89	285	254	159

What the last three winters looked like

The early October numbers only mean something next to what came after them. Here is each of the last three winters, October to February, from the same bulletins:

Winter	Oct	Nov	Dec	Jan	Feb	Winter average	Days above 300	Severe days (above 400)	Worst day
2023-24	219	372	348	355	218	303	91	15	468 on 3 Nov 2023
2024-25	234	374	294	305	214	285	68	14	494 on 18 Nov 2024
2025-26	223	354	351	308	233	295	80	10	461 on 14 Dec 2025

• November is the worst month every year, averaging between 354 and 374, deep in the Very Poor band. December and January stay close behind.
• 2024-25 was the mildest of the three overall at 285, but it also had the single worst day, 494 on 18 Nov 2024.
• 2025-26 had the fewest Severe days (10) but more Very Poor days than 2024-25, so it averaged 295, worse than the year before.
• In every one of the three winters, the second half of October averaged far above the first 17 days: 256, 303, 304 for 18 to 31 October.

What this October does and does not tell you

A clean start has not predicted a clean winter. 2025 had the cleanest early October of the three earlier years, at 157, and still produced a winter average of 295 with 80 days above 300. Stubble burning in Punjab and Haryana peaks in late October and early November, and the cold, still air that traps pollution near the ground sets in at the same time.

Diwali timing also shifts the comparison. Diwali fell on 20 October last year, and Delhi’s AQI that day was 345. This year it falls on 8 November, so the firecracker spike will land in what is already the worst month. The September figures were good too: Delhi recorded its lowest September average in five years, but September has never been the problem.

The honest reading of the first 17 days is that Delhi has gained a few weeks of breathing room, not that this winter will be milder. The comparison that matters will come at the end of November.

For the live reading, IndiaRealTime’s Delhi page shows current AQI next to weather and fuel prices, and the air quality tracker covers cities across India. The Cost of Living and Breathing Index compares 273 cities on live air quality and fuel prices, and IMD weather alerts flag the fog and calm-wind days that usually come with the worst smog. If you want to know what the AQI number itself measures, our guide to how CPCB calculates AQI explains the sub-indices behind it. Elsewhere on IndiaRealTime, our list of India’s 28 states and 8 union territories explains where Delhi fits as a union territory with its own legislature.

FAQs

What is Delhi’s AQI this winter so far? The average for 1 to 17 October 2026 was 152, in the Moderate band, with no Poor day yet.

Is Delhi’s air better this October than last year? Yes for the first 17 days: 152 against 157 in 2025, 177 in 2024 and 188 in 2023. It started worse than all three in the first week, then improved.

Which month has the worst AQI in Delhi? November. It averaged 372, 374, 354 in 2023, 2024 and 2025.

How many Severe AQI days did Delhi have last winter? 10 days above 400 between October 2025 and February 2026, against 14 the winter before and 15 in 2023-24.

When is Diwali in 2026? 8 November, nearly three weeks later than in 2025.

Sources

• CPCB: Daily AQI Bulletin (example, 17 October 2026). All 469 bulletins used follow the same URL pattern by date.
• Tribune India: November AQI averages for 2023, 2024 and 2025, citing CPCB
• India.com: Most polluted start to October in four years
• Business Standard: Lowest September AQI in five years; CAQM winter measures
• All India Radio: GRAP Stage I invoked, October 2024
• All India Radio: GRAP Stage I invoked, October 2025

Updated 18 October 2026 with CPCB bulletins up to 17 October. Our monthly averages are computed from the daily 4 PM bulletins and can differ by a few points from monthly figures CPCB publishes separately; for November 2024 they match exactly at 374.