SmogRank / United States / Mountain View
Mountain View, month by month
Mountain View has a measured daily mean on 182 days since 31 October 2025. Its worst month was January 2026, at 50 US AQI (9.0 µg/m³). Its cleanest was September 2026, at 15 US AQI (2.7 µg/m³).
Every month since 2025
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
7 months
| Month | Why |
|---|---|
| Aug 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. |
| Jul 2026 | 7 of 31 days measured; a month needs 22. The others: 24 with under 18 hours of readings or readings that failed our checks. |
| Jun 2026 | 2 of 30 days measured; a month needs 21. The others: 28 with under 18 hours of readings or readings that failed our checks. |
| May 2026 | 8 of 31 days measured; a month needs 22. The others: 23 with under 18 hours of readings or readings that failed our checks. |
| Apr 2026 | 6 of 30 days measured; a month needs 21. The others: 24 with under 18 hours of readings or readings that failed our checks. |
| Dec 2025 | 19 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks. |
| Oct 2025 | 1 of 31 days measured; a month needs 22. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Mountain View's worst months
| Month | US AQI | Episode |
|---|---|---|
| January 2026 | 509.0 µg/m³ | California, United States, 30 January to 6 February 2026 |
| November 2025 | 448.0 µg/m³ | – |
| February 2026 | 376.6 µg/m³ | California, United States, 30 January to 6 February 2026 |
| March 2026 | 213.7 µg/m³ | – |
| September 2026 | 152.7 µg/m³ | – |
Monthly means over the days measured; finished months only.
Mountain View's worst days
| Day | US AQI | Episode |
|---|---|---|
| 28 Nov 2025 | 8728.6 µg/m³ | – |
| 6 Dec 2025 | 8527.2 µg/m³ | – |
| 31 Jan 2026 | 8527.1 µg/m³ | California, United States, 30 January to 6 February 2026 |
| 5 Feb 2026 | 7823.8 µg/m³ | California, United States, 30 January to 6 February 2026 |
| 27 Nov 2025 | 7823.7 µg/m³ | – |
| 30 Nov 2025 | 7823.4 µg/m³ | – |
| 29 Nov 2025 | 7723.2 µg/m³ | – |
| 7 Dec 2025 | 7723.2 µg/m³ | – |
| 14 Dec 2025 | 7722.8 µg/m³ | – |
| 26 Jan 2026 | 7522.1 µg/m³ | – |
Daily means, the highest since 31 Oct 2025; 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, Mountain View, United States, 31 Oct 2025 – 11 Oct 2026. Monitor data from national networks via OpenAQ and the publishers listed at smogrank.com/sources. smogrank.com/us/mountain-view/history (accessed 14 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.
Mountain View now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-14 00:07 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).