SmogRank / United States / California / La Crescenta-Montrose
La Crescenta-Montrose, month by month
La Crescenta-Montrose has a measured daily mean on 1,105 days since 1 January 2023. Its worst month was May 2024, at 61 US AQI (14.3 µg/m³), 312th of 2,684 cities on that month's world ranking. Its cleanest was January 2023, at 26 US AQI (4.7 µg/m³). 2025 averaged 44 US AQI (8.0 µg/m³), against 52 US AQI (9.9 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
10 months
| Month | Why |
|---|---|
| Aug 2026 | 14 of 31 days measured; a month needs 22. The others: 17 with under 18 hours of readings or readings that failed our checks. |
| Jul 2026 | 11 of 31 days measured; a month needs 22. The others: 20 with under 18 hours of readings or readings that failed our checks. |
| Jun 2026 | 8 of 30 days measured; a month needs 21. The others: 22 with under 18 hours of readings or readings that failed our checks. |
| May 2026 | 12 of 31 days measured; a month needs 22. The others: 19 with under 18 hours of readings or readings that failed our checks. |
| Apr 2026 | 10 of 30 days measured; a month needs 21. The others: 20 with under 18 hours of readings or readings that failed our checks. |
| Jun 2025 | 14 of 30 days measured; a month needs 21. The others: 16 with under 18 hours of readings or readings that failed our checks. |
| May 2025 | 15 of 31 days measured; a month needs 22. The others: 16 with under 18 hours of readings or readings that failed our checks. |
| Jun 2023 | 17 of 30 days measured; a month needs 21. The others: 13 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: 19 missing from OpenAQ's archive, 1 with under 18 hours of readings or readings that failed our checks. |
| Feb 2023 | 1 of 28 days measured; a month needs 20. The others: 25 missing from OpenAQ's archive, 2 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.
La Crescenta-Montrose's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| May 2024 | 6114.3 µg/m³ | 312thof 2,684 | – |
| June 2024 | 6013.7 µg/m³ | 251stof 2,563 | – |
| January 2025 | 5812.8 µg/m³ | 636thof 2,474 | – |
| September 2023 | 5812.7 µg/m³ | 278thof 2,176 | – |
| July 2024 | 5712.4 µg/m³ | 377thof 2,566 | California and Nevada, United States, July 2024 |
| July 2023 | 5611.8 µg/m³ | 424thof 1,432 | California, United States, July 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.
La Crescenta-Montrose's worst days
| Day | US AQI | Episode |
|---|---|---|
| 9 Jan 2025 | 15358.2 µg/m³ | – |
| 6 Aug 2025 | 8929.6 µg/m³ | – |
| 5 Jul 2023 | 8728.6 µg/m³ | California, United States, July 2023 |
| 10 Jan 2025 | 8125.4 µg/m³ | – |
| 5 Jul 2024 | 8125.3 µg/m³ | California and Nevada, United States, July 2024 |
| 4 Dec 2024 | 8125.0 µg/m³ | California and Oregon, United States, December 2024 |
| 9 Jul 2024 | 8024.6 µg/m³ | – |
| 22 Apr 2024 | 8024.4 µg/m³ | – |
| 17 Jan 2024 | 7823.8 µg/m³ | – |
| 16 Oct 2024 | 7823.4 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, La Crescenta-Montrose, United States, 1 Jan 2023 – 11 Oct 2026. Monitor data from Clarity via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/us/la-crescenta-montrose/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.
La Crescenta-Montrose now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 22:07 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).