Riverside Air Quality in Fall
Across 2019–2025, Riverside's fall (September–November) air quality had a median AQI of 88 (Moderate) over 637 monitored days in the Riverside-San Bernardino-Ontario, CA area. 37.4% of fall days (238 of 637) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 48.8% of days. The cleanest fall on record here was 2025 (median AQI 74, 12 days above 100) and the worst was 2020 (median 112, 51 days above 100, peak AQI 340).
- Good: 3.1%
- Moderate: 59.5%
- Unhealthy for Sensitive Groups: 21.2%
- Unhealthy or worse: 16.2%
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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How is the air in Riverside in fall?
Moderate on a typical day: median AQI 88 across 2019–2025, with 37.4% of fall days above AQI 100. Ground-level ozone is the main driver.
- ✓3.1% of fall days were Good (AQI 0–50), 59.5% Moderate (51–100).
- ✓238 days of 637 reached AQI 101+; the fall peak was 593.
- ✓Cleanest month: November; worst month: September.
Frequently asked questions
What is the air quality like in Riverside in fall?▾
Across 2019–2025, the median daily AQI in Riverside in fall was 88 (Moderate). 3.1% of days were Good, 59.5% Moderate, and 37.4% reached Unhealthy for Sensitive Groups or worse, based on 637 monitored days in EPA's Air Quality System.
Is fall a good time for outdoor exercise in Riverside?▾
A typical fall day in Riverside is Moderate (median AQI 88): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 3 of fall days (37.4%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Riverside's fall air quality problems?▾
Ground-level ozone set the daily AQI on 48.8% of fall days in Riverside. The highest fall AQI recorded in 2019–2025 was 593 (Hazardous), in 2020.
Riverside fall air quality, year by year
Riverside fall air quality by year (Riverside-San Bernardino-Ontario, CA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 91 | 93 | 38 | 195 | O3 |
| 2020worst | 91 | 112 | 51 | 340 | O3 |
| 2021 | 91 | 90 | 33 | 486 | O3 |
| 2022 | 91 | 71 | 24 | 406 | O3 |
| 2023 | 91 | 82 | 34 | 228 | O3 |
| 2024 | 91 | 101 | 46 | 593 | O3 |
| 2025cleanest | 91 | 74 | 12 | 166 | O3 |
What fall air means in Riverside
A typical fall day in Riverside is Moderate (median AQI 88): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 3 of fall days (37.4%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Fall's median AQI of 88 is in line with Riverside's whole-year median of 89, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median Fall AQI across every EPA metro area (296,275 metro-days, 2019–2025) is 40, so Riverside runs above the national Fall norm; 37.4% of its Fall days topped AQI 100 versus 1.5% nationally (above average).
Within the season, November is the cleanest month (median AQI 71, 14.8% of days above 100) and September the worst (median 122, 61.4% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Riverside
The latest EPA AirNow observation puts Riverside's AQI at 58 (PM2.5). The figures above are multi-year season statistics, 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.