SmogRank / United States / California / Hawthorne
Hawthorne, month by month
Hawthorne has a measured daily mean on 1,104 days since 1 January 2023. Its worst month was December 2024, at 74 US AQI (21.5 µg/m³), 210th of 2,616 cities on that month's world ranking. Its cleanest was March 2024, at 39 US AQI (7.0 µg/m³). 2025 averaged 57 US AQI (12.5 µg/m³), against 55 US AQI (11.5 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.
Hawthorne's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| December 2024 | 7421.5 µg/m³ | 210thof 2,616 | South-western United States and Mexico, December 2024 to January 2025 California, United States, December 2024and 1 more |
| January 2025 | 7220.4 µg/m³ | 290thof 2,474 | California, United States, January 2025 South-western United States and Mexico, December 2024 to January 2025 |
| December 2025 | 7119.8 µg/m³ | 515thof 3,006 | Western United States and Mexico, December 2025 |
| November 2025 | 6416.0 µg/m³ | 548thof 2,715 | California, United States, November 2025 |
| December 2023 | 6315.4 µg/m³ | 272ndof 2,247 | Western United States and Mexico, December 2023 |
| October 2024 | 6215.1 µg/m³ | 251stof 2,020 | – |
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.
Hawthorne's worst days
| Day | US AQI | Episode |
|---|---|---|
| 8 Jan 2025 | 15460.2 µg/m³ | – |
| 25 Dec 2023 | 13147.6 µg/m³ | Western United States and Mexico, December 2023 |
| 17 Dec 2025 | 10637.6 µg/m³ | Western United States and Mexico, December 2025 |
| 9 Jan 2025 | 10236.0 µg/m³ | – |
| 10 Nov 2024 | 10035.3 µg/m³ | California, United States, November 2024 |
| 31 Dec 2024 | 9633.0 µg/m³ | South-western United States and Mexico, December 2024 to January 2025 |
| 30 Nov 2025 | 9532.6 µg/m³ | – |
| 6 Dec 2024 | 9532.5 µg/m³ | California and Oregon, United States, December 2024 |
| 18 Dec 2025 | 9432.4 µg/m³ | Western United States and Mexico, December 2025 |
| 13 Dec 2025 | 9432.2 µg/m³ | Western United States and Mexico, December 2025 |
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, Hawthorne, United States, 1 Jan 2023 – 11 Oct 2026. Monitor data from Clarity and AirGradient via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/us/hawthorne/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.
Hawthorne now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 23:07 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).