SmogRank / United States / California / Ukiah
Ukiah, month by month
Ukiah has a measured daily mean on 1,270 days since 1 January 2023. Its worst month was January 2025, at 60 US AQI (13.8 µg/m³), 566th of 2,474 cities on that month's world ranking. Its cleanest was June 2026, at 22 US AQI (4.0 µg/m³). 2025 averaged 42 US AQI (7.6 µg/m³), against 45 US AQI (8.1 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
1 month
| Month | Why |
|---|---|
| Oct 2024 | 21 of 31 days measured; a month needs 22. The others: 10 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.
Ukiah's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| January 2025 | 6013.8 µg/m³ | 566thof 2,474 | – |
| August 2023 | 5712.5 µg/m³ | 301stof 1,980 | North-western United States and Canada, August 2023 |
| November 2024 | 5712.2 µg/m³ | 559thof 2,624 | – |
| July 2023 | 5511.5 µg/m³ | 467thof 1,432 | – |
| December 2025 | 5511.0 µg/m³ | 1,131stof 3,006 | – |
| January 2026 | 5410.6 µg/m³ | 1,021stof 2,617 | – |
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.
Ukiah's worst days
| Day | US AQI | Episode |
|---|---|---|
| 29 Nov 2024 | 193116.0 µg/m³ | – |
| 22 Jul 2025 | 16169.5 µg/m³ | – |
| 30 Aug 2023 | 13047.2 µg/m³ | North-western United States and Canada, August 2023 |
| 31 Aug 2023 | 10135.6 µg/m³ | North-western United States and Canada, August 2023 |
| 20 Aug 2024 | 9331.8 µg/m³ | – |
| 22 Sept 2023 | 9029.8 µg/m³ | California and Oregon, United States, September 2023 |
| 20 Jul 2023 | 8728.6 µg/m³ | – |
| 21 Sept 2023 | 8527.4 µg/m³ | California and Oregon, United States, September 2023 |
| 28 Sept 2025 | 8225.8 µg/m³ | – |
| 20 Sept 2023 | 8125.1 µg/m³ | California and Oregon, United States, September 2023 |
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, Ukiah, 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/ukiah/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.
Ukiah now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 18:07 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).