SmogRank / Switzerland / Zurich / Winterthur
Winterthur, month by month
Winterthur has a measured daily mean on 720 days since 5 September 2024. Its worst month was January 2026, at 78 US AQI (23.7 µg/m³), 283rd of 2,617 cities on that month's world ranking. Its cleanest was September 2026, at 27 US AQI (4.9 µg/m³).
Every month since 2024
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
Months without a mean, and why
2 months
| Month | Why |
|---|---|
| Feb 2025 | 17 of 28 days measured; a month needs 20. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| Jan 2025 | 9 of 31 days measured; a month needs 22. The others: 22 with under 18 hours of readings or readings that failed our checks. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Winterthur's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| January 2026 | 7823.7 µg/m³ | 283rdof 2,617 | Europe, January and February 2026 |
| December 2025 | 7622.6 µg/m³ | 419thof 3,006 | Eastern Europe, 16 to 21 December 2025 |
| March 2025 | 7622.5 µg/m³ | 479thof 2,862 | Europe, 14 February to 1 March 2025 |
| December 2024 | 7220.5 µg/m³ | 247thof 2,616 | Europe, 24 December 2024 to 3 January 2025 |
| March 2026 | 6918.5 µg/m³ | 653rdof 2,971 | Europe, 18 to 25 March 2026 Europe, 1 to 12 March 2026 |
| November 2024 | 6616.9 µg/m³ | 336thof 2,624 | Europe, November 2024 |
Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.
Winterthur's worst days
| Day | US AQI | Episode |
|---|---|---|
| 1 Jan 2025 | 17184.2 µg/m³ | Europe, 24 December 2024 to 3 January 2025 |
| 20 Feb 2025 | 13850.7 µg/m³ | Europe, 14 February to 1 March 2025 |
| 19 Feb 2025 | 13850.4 µg/m³ | Europe, 14 February to 1 March 2025 |
| 31 Dec 2024 | 13549.4 µg/m³ | Europe, 24 December 2024 to 3 January 2025 |
| 16 Feb 2025 | 13348.3 µg/m³ | Europe, 14 February to 1 March 2025 |
| 1 Jan 2026 | 12545.2 µg/m³ | – |
| 15 Feb 2025 | 12244.0 µg/m³ | Europe, 14 February to 1 March 2025 |
| 17 Feb 2025 | 12143.8 µg/m³ | Europe, 14 February to 1 March 2025 |
| 7 Jan 2026 | 11943.0 µg/m³ | – |
| 18 Feb 2025 | 11942.7 µg/m³ | Europe, 14 February to 1 March 2025 |
Daily means, the highest since 5 Sept 2024; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.
Use this history
SmogRank, PM2.5 monthly and daily means, Winterthur, Switzerland, 5 Sep 2024 – 11 Oct 2026. Monitor data from AirGradient via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/ch/winterthur/history (accessed 12 Oct 2026).
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.
Winterthur now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 18:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published (why we use them).