SmogRank / United States / California / Rancho Murieta
Rancho Murieta, month by month
Rancho Murieta has a measured daily mean on 1,273 days since 1 January 2023. Its worst month was January 2026, at 55 US AQI (11.5 µg/m³), 959th of 2,617 cities on that month's world ranking. Its cleanest was October 2024, at 18 US AQI (3.3 µg/m³). 2025 averaged 34 US AQI (6.2 µg/m³), against 28 US AQI (5.1 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
3 months
| Month | Why |
|---|---|
| Mar 2023 | 10 of 31 days measured; a month needs 22. The others: 1 with readings for part of the day (a day needs 18 hours), 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 | 21 of 31 days measured; a month needs 22. The others: 4 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.
Rancho Murieta's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| January 2026 | 5511.5 µg/m³ | 959thof 2,617 | – |
| January 2025 | 5410.8 µg/m³ | 869thof 2,474 | – |
| December 2024 | 5310.0 µg/m³ | 888thof 2,616 | – |
| December 2023 | 478.4 µg/m³ | 1,141stof 2,247 | – |
| December 2025 | 478.4 µg/m³ | 1,734thof 3,006 | – |
| September 2023 | 448.0 µg/m³ | 1,121stof 2,176 | California and Oregon, United States, September 2023 |
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.
Rancho Murieta's worst days
| Day | US AQI | Episode |
|---|---|---|
| 20 Sept 2023 | 9834.1 µg/m³ | California and Oregon, United States, September 2023 |
| 22 Sept 2023 | 8929.3 µg/m³ | California and Oregon, United States, September 2023 |
| 21 Sept 2023 | 8427.0 µg/m³ | California and Oregon, United States, September 2023 |
| 14 Jan 2026 | 7622.4 µg/m³ | – |
| 23 Sept 2023 | 7421.4 µg/m³ | California and Oregon, United States, September 2023 |
| 6 Dec 2025 | 7421.3 µg/m³ | – |
| 31 Aug 2023 | 7220.6 µg/m³ | – |
| 18 Jan 2026 | 7220.6 µg/m³ | – |
| 17 Jan 2026 | 7119.8 µg/m³ | – |
| 7 Dec 2024 | 7119.7 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, Rancho Murieta, 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/rancho-murieta/history (accessed 13 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.
Rancho Murieta now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-13 05:07 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).