Rancho Cucamonga, California Air Quality
Rancho Cucamonga air quality today — the AQI, the main pollutant, and whether it’s safe to exercise outside right now
Rancho Cucamonga, CA · Air quality right now
The air quality index in Rancho Cucamonga, CA is 61 (Moderate) right now — acceptable for most people.
Is it safe to be outside in Rancho Cucamonga today?
AQI 61 Yes — air quality is Moderate
Fine for most; unusually sensitive people can take it easy.Main pollutant: PM2.5Observed 8:00 AM PDT
Pollutants right now
- PM2.525 µg/m³Main pollutantfine particles — smoke, exhaust, soot
- PM1028 µg/m³coarse particles — dust, pollen, ash
- Ozone20 µg/m³smog — builds on hot, sunny days
- NO₂37 µg/m³nitrogen dioxide — traffic, combustion
ExerciseOK to run for most; sensitive athletes can ease the intensity.
How to read Rancho Cucamonga’s air quality
Guides: The AQI Scale, Explained · Air Quality Alerts, Decoded · How to Read a Wildfire Smoke Map · Why Wildfire Smoke Travels 1,000 Miles.
Air quality over time in Rancho Cucamonga
Across the EPA’s county records from 2020 to 2025, Rancho Cucamonga’s cleanest year was 2023 (median AQI 71) and its most polluted was 2020 (median AQI 93); the typical (median) day has trended cleaner since 2020.
| Year | Median AQI | Unhealthy+ | Main pollutant | USG | Moderate | Good |
|---|---|---|---|---|---|---|
| 2020 | 93 | 87 | Ozone | 76 | 170 | 33 |
| 2021 | 87 | 73 | Ozone | 73 | 202 | 17 |
| 2022 | 77 | 63 | Ozone | 67 | 212 | 23 |
| 2023 | 71 | 51 | Ozone | 67 | 197 | 50 |
| 2024 | 87 | 88 | Ozone | 56 | 182 | 40 |
| 2025 | 77 | 43 | Ozone | 67 | 209 | 46 |
“USG” is Unhealthy for Sensitive Groups (AQI 101–150); “Unhealthy+” combines the Unhealthy, Very Unhealthy, and Hazardous days. In 2024 the EPA tightened the annual fine-particle (PM2.5) standard to 9 µg/m³ from the previous 12 µg/m³, so counties near the old limit read worse against the new one. Source: EPA AQS annual summaries, 2020–2025.
Frequently asked
- What was the worst year for air quality in Rancho Cucamonga?
- In the EPA's 2020–2025 county records, 2020 had the most days above AQI 100: 163 days (76 Unhealthy for Sensitive Groups, 87 Unhealthy or worse). It also had the highest median AQI, 93.
- How many unhealthy air days does Rancho Cucamonga have?
- Across 2020–2025, 37% of the days reported for Rancho Cucamonga's county had an AQI above 100 (811 of 2192), about 135 days a year. 2025 had 110 days.
- What's the main air pollutant in Rancho Cucamonga?
- Ozone: it drove Rancho Cucamonga's county AQI on the most days in every year of the EPA's 2020–2025 records.