Riverside Best & Worst AQI Days: Air Quality Guide
The worst air quality day on record for Riverside (Riverside-San Bernardino-Ontario, CA area) was May 28, 2022, when the daily AQI reached 1683 (Hazardous), set by coarse dust (PM10). Across 2,557 monitored days in 2019–2025, 10 of the 10 worst days were Unhealthy (AQI 151+) or worse; 9 of the 10 were driven by coarse dust (PM10) and 1 by fine particulate matter (PM2.5), and 4 of them fell in 2022. The cleanest day was March 15, 2023 at AQI 35 (Good); the 10 best days span 5 different years.
Extra Protection for Riverside Homes
Air quality in Riverside is moderate (AQI 58), with fine particles (PM2.5) the main concern. A True-HEPA purifier gives sensitive groups — kids, seniors and anyone with asthma or allergies — cleaner air indoors on days like today.
Recommended: Coway AP-1512HH Mighty — True HEPA + carbon · CADR ~246 CFM · rooms up to 361 sq ft
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When were Riverside's worst and best air quality days?
Worst: May 28, 2022, AQI 1683 (Hazardous, PM10). Best: March 15, 2023, AQI 35 (Good). Based on 2,557 EPA-monitored days in the Riverside-San Bernardino-Ontario, CA area, 2019–2025.
- ✓10 of the 10 worst days were Unhealthy (AQI 151+) or worse; the 10th-worst was AQI 486 (Hazardous).
- ✓Coarse dust (PM10) drove 9 of the 10 worst days.
- ✓2022 accounts for 4 of the 10 worst days.
Frequently asked questions
What was the worst air quality day in Riverside?▾
May 28, 2022: the Riverside-San Bernardino-Ontario, CA area's daily AQI hit 1683 (Hazardous), driven by coarse dust (PM10). That is the highest of 2,557 monitored days in 2019–2025.
What was the best air quality day in Riverside?▾
March 15, 2023, with a daily AQI of 35 (Good). The daily AQI is the highest reading from any monitor in the area, so even the cleanest day reflects the area's worst monitor.
What was Riverside's worst air quality day in 2025?▾
January 7, 2025, AQI 365 (Hazardous), set by coarse dust (PM10).
Which pollutant causes Riverside's worst air days?▾
Coarse dust (PM10) set the AQI on 9 of the 10 worst days; fine particulate matter (PM2.5) on 1. The tables above list the defining pollutant for every day.
Riverside's 10 worst air quality days, 2019–2025
Highest daily AQI recorded for the Riverside-San Bernardino-Ontario, CA area (EPA AQS). The daily AQI is the highest reading from any monitor in the area that day.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2022 page) | 1683 | Hazardous | PM10 — coarse dust (PM10) |
| 2 | (2022 page) | 1548 | Hazardous | PM10 — coarse dust (PM10) |
| 3 | (2022 page) | 792 | Hazardous | PM10 — coarse dust (PM10) |
| 4 | (2023 page) | 660 | Hazardous | PM10 — coarse dust (PM10) |
| 5 | (2022 page) | 660 | Hazardous | PM10 — coarse dust (PM10) |
| 6 | (2024 page) | 593 | Hazardous | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 7 | (2020 page) | 584 | Hazardous | PM10 — coarse dust (PM10) |
| 8 | (2023 page) | 517 | Hazardous | PM10 — coarse dust (PM10) |
| 9 | (2023 page) | 507 | Hazardous | PM10 — coarse dust (PM10) |
| 10 | (2021 page) | 486 | Hazardous | PM10 — coarse dust (PM10) |
Worst day of each year in Riverside
The single highest-AQI day in each year on record. Click a year for its full month-by-month statistics.
| Year | Worst day | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 2019 | 213 | Very Unhealthy | O3 — ground-level ozone, in peak ozone season | |
| 2020 | 584 | Hazardous | PM10 — coarse dust (PM10) | |
| 2021 | 486 | Hazardous | PM10 — coarse dust (PM10) | |
| 2022 | 1683 | Hazardous | PM10 — coarse dust (PM10) | |
| 2023 | 660 | Hazardous | PM10 — coarse dust (PM10) | |
| 2024 | 593 | Hazardous | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2025 | 365 | Hazardous | PM10 — coarse dust (PM10) |
Riverside's 10 best air quality days, 2019–2025
Lowest daily AQI recorded for the Riverside-San Bernardino-Ontario, CA area. Ties are listed most recent first.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2023 page) | 35 | Good | O3 — ground-level ozone |
| 2 | (2025 page) | 38 | Good | O3 — ground-level ozone |
| 3 | (2024 page) | 38 | Good | O3 — ground-level ozone |
| 4 | (2025 page) | 39 | Good | O3 — ground-level ozone |
| 5 | (2025 page) | 39 | Good | O3 — ground-level ozone |
| 6 | (2024 page) | 39 | Good | O3 — ground-level ozone |
| 7 | (2023 page) | 39 | Good | O3 — ground-level ozone |
| 8 | (2019 page) | 39 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 9 | (2020 page) | 40 | Good | O3 — ground-level ozone |
| 10 | (2025 page) | 41 | Good | PM2.5 — fine particulate matter (PM2.5) |
Right now in Riverside
The latest EPA AirNow observation puts Riverside's AQI at 58 (PM2.5). The days above are historical records, not today's reading.
View current Riverside air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Riverside-San Bernardino-Ontario, CA), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.