SmogRank / United States / California / Fremont
Fremont, month by month
Fremont has a measured daily mean on 362 days since 19 September 2025. Its worst month was January 2026, at 63 US AQI (15.3 µg/m³), 743rd of 2,617 cities on that month's world ranking. Its cleanest was April 2026, at 7 US AQI (1.3 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
2 months
| Month | Why |
|---|---|
| Oct 2025 | 14 of 31 days measured; a month needs 22. The others: 17 with under 18 hours of readings or readings that failed our checks. |
| Sep 2025 | 12 of 30 days measured; a month needs 21. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Fremont's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| January 2026 | 6315.3 µg/m³ | 743rdof 2,617 | California, United States, 30 January to 6 February 2026 California, United States, 26 to 27 January 2026and 1 more |
| December 2025 | 6114.4 µg/m³ | 767thof 3,006 | California, United States, December 2025 |
| November 2025 | 5712.2 µg/m³ | 746thof 2,715 | – |
| February 2026 | 488.7 µg/m³ | 1,771stof 2,866 | California, United States, 30 January to 6 February 2026 |
| August 2026 | 397.0 µg/m³ | 2,099thof 2,896 | – |
| July 2026 | 325.7 µg/m³ | 2,491stof 2,784 | – |
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.
Fremont's worst days
| Day | US AQI | Episode |
|---|---|---|
| 31 Jan 2026 | 11842.6 µg/m³ | California, United States, 30 January to 6 February 2026 |
| 5 Feb 2026 | 11039.1 µg/m³ | California, United States, 30 January to 6 February 2026 |
| 26 Jan 2026 | 10035.3 µg/m³ | California, United States, 26 to 27 January 2026 |
| 28 Nov 2025 | 9935.1 µg/m³ | – |
| 1 Feb 2026 | 9834.4 µg/m³ | California, United States, 30 January to 6 February 2026 |
| 27 Nov 2025 | 9834.1 µg/m³ | – |
| 4 Feb 2026 | 9734.0 µg/m³ | California, United States, 30 January to 6 February 2026 |
| 6 Dec 2025 | 9331.7 µg/m³ | California, United States, December 2025 |
| 23 Jan 2026 | 9331.6 µg/m³ | – |
| 25 Nov 2025 | 9230.9 µg/m³ | – |
Daily means, the highest since 19 Sept 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, Fremont, United States, 19 Sep 2025 – 11 Oct 2026. Monitor data from AirGradient via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/us/fremont/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.
Fremont now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 19:07 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).