SmogRank / United States / California / Yreka
Yreka, month by month
Yreka has a measured daily mean on 1,281 days since 5 January 2023. Its worst month was August 2023, at 114 US AQI (40.8 µg/m³), 32nd of 1,980 cities on that month's world ranking. Its cleanest was May 2026, at 15 US AQI (2.7 µg/m³). 2025 averaged 38 US AQI (6.9 µg/m³), against 33 US AQI (5.9 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
3 months
| Month | Why |
|---|---|
| Mar 2023 | 11 of 31 days measured; a month needs 22. The others: 20 missing from OpenAQ's archive. |
| Feb 2023 | 1 of 28 days measured; a month needs 20. The others: 2 with readings for part of the day (a day needs 18 hours), 25 missing from OpenAQ's archive. |
| Jan 2023 | 20 of 31 days measured; a month needs 22. The others: 1 with readings for part of the day (a day needs 18 hours), 6 missing from OpenAQ's archive. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Yreka's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| August 2023 | 11440.8 µg/m³ | 32ndof 1,980 | North-western United States and Canada, August 2023 |
| September 2023 | 7320.7 µg/m³ | 91stof 2,176 | Oregon and California, United States, September 2023 |
| January 2026 | 5712.5 µg/m³ | 905thof 2,617 | – |
| December 2023 | 5712.3 µg/m³ | 413thof 2,247 | California and Oregon, United States, December 2023 |
| December 2025 | 5712.3 µg/m³ | 930thof 3,006 | – |
| July 2024 | 5611.6 µg/m³ | 471stof 2,566 | North-western United States and Canada, July 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.
Yreka's worst days
| Day | US AQI | Episode |
|---|---|---|
| 28 Aug 2023 | 310230.0 µg/m³ | North-western United States and Canada, August 2023 |
| 23 Sept 2023 | 254179.0 µg/m³ | Oregon and California, United States, September 2023 |
| 29 Aug 2023 | 219144.0 µg/m³ | North-western United States and Canada, August 2023 |
| 27 Aug 2023 | 201126.0 µg/m³ | North-western United States and Canada, August 2023 |
| 18 Aug 2023 | 18299.3 µg/m³ | North-western United States and Canada, August 2023 |
| 24 Sept 2023 | 17894.0 µg/m³ | Oregon and California, United States, September 2023 |
| 23 Aug 2023 | 17285.8 µg/m³ | North-western United States and Canada, August 2023 |
| 19 Aug 2023 | 16879.2 µg/m³ | North-western United States and Canada, August 2023 |
| 31 Aug 2025 | 16676.4 µg/m³ | North-western United States and Canada, August and September 2025 |
| 25 Aug 2023 | 15764.3 µg/m³ | North-western United States and Canada, August 2023 |
Daily means, the highest since 5 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, Yreka, United States, 5 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/yreka/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.
Yreka now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 20:07 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).