SmogRank / United States / California / El Rio
El Rio, month by month
El Rio has a measured daily mean on 848 days since 1 January 2023. Its worst month was November 2024, at 52 US AQI (9.7 µg/m³), 909th of 2,624 cities on that month's world ranking. Its cleanest was April 2026, at 24 US AQI (4.3 µg/m³).
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
19 months
| Month | Why |
|---|---|
| Jul 2024 | 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 2024 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| May 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Apr 2024 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Mar 2024 | No day measured. The others: 1 missing from OpenAQ's archive, 30 with under 18 hours of readings or readings that failed our checks. |
| Feb 2024 | No day measured. The others: 1 missing from OpenAQ's archive, 28 with under 18 hours of readings or readings that failed our checks. |
| Jan 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Dec 2023 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Nov 2023 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Oct 2023 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Sep 2023 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Aug 2023 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jul 2023 | No day measured. The others: 1 missing from OpenAQ's archive, 30 with under 18 hours of readings or readings that failed our checks. |
| Jun 2023 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| May 2023 | 6 of 31 days measured; a month needs 22. The others: 25 with under 18 hours of readings or readings that failed our checks. |
| Apr 2023 | 14 of 30 days measured; a month needs 21. The others: 3 missing from OpenAQ's archive, 13 with under 18 hours of readings or readings that failed our checks. |
| Mar 2023 | 7 of 31 days measured; a month needs 22. The others: 20 missing from OpenAQ's archive, 4 with under 18 hours of readings or readings that failed our checks. |
| Feb 2023 | No day measured. The others: 25 missing from OpenAQ's archive, 3 with under 18 hours of readings or readings that failed our checks. |
| Jan 2023 | 13 of 31 days measured; a month needs 22. The others: 7 missing from OpenAQ's archive, 11 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.
El Rio's worst months
| Month | US AQI | World rank |
|---|---|---|
| November 2024 | 529.7 µg/m³ | 909thof 2,624 |
| May 2025 | 519.3 µg/m³ | 1,031stof 2,826 |
| June 2025 | 519.2 µg/m³ | 1,543rdof 2,508 |
| October 2025 | 498.8 µg/m³ | 706thof 2,614 |
| August 2025 | 478.5 µg/m³ | 1,639thof 2,901 |
| November 2025 | 478.5 µg/m³ | 1,389thof 2,715 |
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.
El Rio's worst days
| Day | US AQI | Episode |
|---|---|---|
| 6 Nov 2024 | 16677.3 µg/m³ | – |
| 22 Jan 2025 | 15560.9 µg/m³ | California, United States, January 2025 |
| 7 Nov 2024 | 13147.8 µg/m³ | – |
| 9 Nov 2024 | 6818.2 µg/m³ | – |
| 5 Dec 2024 | 6717.7 µg/m³ | – |
| 8 Nov 2024 | 6617.0 µg/m³ | – |
| 3 Nov 2025 | 6516.7 µg/m³ | – |
| 8 Nov 2025 | 6516.4 µg/m³ | – |
| 5 Aug 2025 | 6315.5 µg/m³ | – |
| 16 Jun 2025 | 6215.2 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, El Rio, 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/el-rio/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.
El Rio 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).