SmogRank / United States / California / Atascadero
Atascadero, month by month
Atascadero has a measured daily mean on 1,338 days since 1 January 2023. Its worst month was December 2024, at 54 US AQI (10.6 µg/m³), 806th of 2,616 cities on that month's world ranking. Its cleanest was July 2025, at 7 US AQI (1.2 µg/m³). 2025 averaged 26 US AQI (4.6 µg/m³), against 29 US AQI (5.3 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
Atascadero's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| December 2024 | 5410.6 µg/m³ | 806thof 2,616 | – |
| January 2025 | 5310.3 µg/m³ | 940thof 2,474 | – |
| November 2024 | 468.2 µg/m³ | 1,296thof 2,624 | – |
| January 2026 | 458.1 µg/m³ | 1,462ndof 2,617 | – |
| September 2023 | 417.3 µg/m³ | 1,385thof 2,176 | California and Oregon, United States, September 2023 |
| August 2026 | 417.3 µg/m³ | 1,948thof 2,896 | – |
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.
Atascadero's worst days
| Day | US AQI | Episode |
|---|---|---|
| 21 Sept 2023 | 8828.7 µg/m³ | California and Oregon, United States, September 2023 |
| 31 Aug 2026 | 7924.1 µg/m³ | – |
| 22 Sept 2023 | 7924.0 µg/m³ | California and Oregon, United States, September 2023 |
| 20 Sept 2023 | 7723.3 µg/m³ | California and Oregon, United States, September 2023 |
| 6 Dec 2024 | 7421.4 µg/m³ | – |
| 23 Sept 2023 | 7019.3 µg/m³ | California and Oregon, United States, September 2023 |
| 8 Dec 2024 | 6818.4 µg/m³ | – |
| 5 Dec 2024 | 6616.9 µg/m³ | – |
| 7 Dec 2024 | 6516.6 µg/m³ | – |
| 22 Jan 2025 | 6516.6 µg/m³ | – |
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, Atascadero, United States, 1 Jan 2023 – 11 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/atascadero/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.
Atascadero now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 23:07 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).