SmogRank / Mexico / Guanajuato / Celaya
Celaya, month by month
Celaya has a measured daily mean on 1,098 days since 1 January 2023. Its worst month was May 2023, at 107 US AQI (37.9 µg/m³), 37th of 1,600 cities on that month's world ranking. Its cleanest was September 2025, at 52 US AQI (9.5 µg/m³). 2025 averaged 65 US AQI (16.4 µg/m³), against 79 US AQI (24.1 µg/m³) in 2024.
Every month since 2023
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
10 months
| Month | Why |
|---|---|
| Feb 2026 | 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 2026 | 18 of 31 days measured; a month needs 22. The others: 13 with under 18 hours of readings or readings that failed our checks. |
| Aug 2025 | 20 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| Jun 2025 | 17 of 30 days measured; a month needs 21. The others: 13 with under 18 hours of readings or readings that failed our checks. |
| Sep 2024 | 6 of 30 days measured; a month needs 21. The others: 24 with under 18 hours of readings or readings that failed our checks. |
| Aug 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jul 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jun 2024 | 19 of 30 days measured; a month needs 21. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| Mar 2023 | 11 of 31 days measured; a month needs 22. The others: 20 missing from OpenAQ's archive. |
| Feb 2023 | 3 of 28 days measured; a month needs 20. The others: 25 missing from OpenAQ's archive. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Celaya's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| May 2023 | 10737.9 µg/m³ | 37thof 1,600 | Guanajuato and Jalisco, Mexico, May 2023 |
| April 2023 | 10537.0 µg/m³ | 22ndof 1,622 | – |
| January 2023 | 9934.6 µg/m³ | 48thof 1,261 | Southern Mexico, January 2023 |
| May 2024 | 9633.1 µg/m³ | 60thof 2,684 | – |
| April 2024 | 9331.6 µg/m³ | 69thof 2,520 | – |
| March 2024 | 8628.0 µg/m³ | 47thof 1,698 | – |
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.
Celaya's worst days
| Day | US AQI | Episode |
|---|---|---|
| 1 Jan 2024 | 18197.6 µg/m³ | Southern Mexico, January 2024 |
| 1 Jan 2023 | 17386.7 µg/m³ | – |
| 25 Dec 2023 | 16170.4 µg/m³ | Southern Mexico, December 2023 |
| 25 Dec 2024 | 15865.2 µg/m³ | Guanajuato, México and Mexico City, Mexico, December 2024 |
| 5 Apr 2024 | 15459.3 µg/m³ | – |
| 21 Jan 2023 | 15358.6 µg/m³ | Southern Mexico, January 2023 |
| 3 May 2023 | 15358.6 µg/m³ | Guanajuato and Jalisco, Mexico, May 2023 |
| 20 Jan 2023 | 15256.4 µg/m³ | Southern Mexico, January 2023 |
| 10 May 2024 | 15155.6 µg/m³ | – |
| 4 May 2023 | 14252.3 µg/m³ | Guanajuato and Jalisco, Mexico, May 2023 |
Daily means, the highest since 1 Jan 2023; 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, Celaya, Mexico, 1 Jan 2023 – 11 Oct 2026. Monitor data from Sinaica Mexico via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/mx/celaya/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.
Celaya now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 17:07 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).