SmogRank / United States / California / Porterville
Porterville, month by month
Porterville has a measured daily mean on 1,281 days since 1 January 2023. Its worst month was December 2024, at 76 US AQI (22.6 µg/m³), 182nd of 2,616 cities on that month's world ranking. Its cleanest was March 2024, at 29 US AQI (5.3 µg/m³). 2025 averaged 53 US AQI (10.4 µg/m³), against 55 US AQI (11.4 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
2 months
| Month | Why |
|---|---|
| Mar 2023 | 11 of 31 days measured; a month needs 22. The others: 20 missing from OpenAQ's archive. |
| 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.
Porterville's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| December 2024 | 7622.6 µg/m³ | 182ndof 2,616 | California, United States, December 2024 California and Oregon, United States, December 2024 |
| January 2025 | 6315.5 µg/m³ | 462ndof 2,474 | Western United States and Mexico, January and February 2025 California, United States, January 2025 |
| March 2026 | 6215.0 µg/m³ | 843rdof 2,971 | – |
| January 2026 | 6214.9 µg/m³ | 765thof 2,617 | California, United States, 30 January to 6 February 2026 California and Oregon, United States, January 2026 |
| December 2023 | 6114.3 µg/m³ | 304thof 2,247 | Western United States and Mexico, December 2023 California and Oregon, United States, December 2023 |
| July 2024 | 5913.6 µg/m³ | 249thof 2,566 | – |
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.
Porterville's worst days
| Day | US AQI | Episode |
|---|---|---|
| 6 Dec 2024 | 14954.8 µg/m³ | California and Oregon, United States, December 2024 |
| 8 Dec 2024 | 14754.2 µg/m³ | California and Oregon, United States, December 2024 |
| 7 Dec 2024 | 14553.2 µg/m³ | California and Oregon, United States, December 2024 |
| 5 Dec 2024 | 14051.5 µg/m³ | California and Oregon, United States, December 2024 |
| 3 Dec 2024 | 12947.0 µg/m³ | California and Oregon, United States, December 2024 |
| 4 Dec 2024 | 12545.2 µg/m³ | California and Oregon, United States, December 2024 |
| 2 Dec 2024 | 10436.8 µg/m³ | California and Oregon, United States, December 2024 |
| 1 Dec 2024 | 9834.2 µg/m³ | California and Oregon, United States, December 2024 |
| 20 Mar 2026 | 9733.8 µg/m³ | – |
| 9 Dec 2024 | 9633.1 µg/m³ | California and Oregon, United States, December 2024 |
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, Porterville, 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/porterville/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.
Porterville now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 21:07 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).