Pasadena, California Air Quality Forecast - Today, Tomorrow
Air Quality Today
Today (10 October): Air quality in Pasadena, California is fair. AQI, PM10, and O3 are fair; PM2.5, NO2, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 2:00 PM (PM10: 26.6/100).
Air Quality Tomorrow
Tomorrow (11 October 2026): Air quality in Pasadena, California is fair. PM2.5 increases to fair; O3 decreases to good; all other pollutants stay as today. Pollution peaks around 8:00 AM (PM10: 34.2/100).
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Air Quality
Today - 10 October
| Pollutant | Level | Value |
|---|---|---|
| AQI | Fair | 26.6/100 |
| PM2.5 (fine particles) | Good | 16.8/100 |
| PM10 (coarse particles) | Fair | 26.6/100 |
| NO2 (nitrogen dioxide) | Good | 7.6/100 |
| O3 (ozone) | Fair | 22.9/100 |
| SO2 (sulfur dioxide) | Good | 0.6/100 |
| CO (carbon monoxide) | Good | 0.5/100 |
| HCHO (formaldehyde) | Good | 1.5/100 |
| PM1 (ultrafine particles) | Good | 3.0/100 |
Tomorrow - 11 October
| Pollutant | Level | Value |
|---|---|---|
| AQI | Fair | 34.2/100 |
| PM2.5 (fine particles) | Fair | 26.1/100 |
| PM10 (coarse particles) | Fair | 34.2/100 |
| NO2 (nitrogen dioxide) | Good | 9.1/100 |
| O3 (ozone) | Good | 19.2/100 |
| SO2 (sulfur dioxide) | Good | 0.7/100 |
| CO (carbon monoxide) | Good | 0.5/100 |
| HCHO (formaldehyde) | Good | 1.4/100 |
| PM1 (ultrafine particles) | Good | 4.8/100 |
Local Environmental Conditions
Around the heart of Pasadena, California, dense development means road traffic is the main local source of nitrogen dioxide and fine particles. Its setting in the Gabriel Valley, ringed by mountains, means cold air and pollution can get trapped close to the ground during calm spells. Traffic on I-210 and SR-134 adds to local emissions.
From January to March, cooler, still nights at around 12°C allow pollution to collect in the valley. Later in the year, warm, sunny weather from June to September, around 25°C at its peak, raises afternoon ozone levels. Wildfire smoke is most likely from April to October, sometimes turning the sky hazy for days.
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Frequently Asked Questions About Air Quality in California
Is air quality bad in Pasadena, California right now?
On 10 October 2026, overall air quality in Pasadena, California is fair. AQI is the main air quality indicator at 26.6/100. Pollution peaks around 2:00 PM (PM10: 26.6/100).
Will air quality be worse tomorrow in Pasadena, California?
On 11 October 2026, air quality conditions in Pasadena, California will be similar to today, with AQI forecast at fair at 34.2/100. Pollution peaks around 8:00 AM (PM10: 34.2/100).
When is air pollution at its worst in Pasadena, California?
From January to March, cooler, still nights at around 12°C allow pollution to collect in the valley. Later in the year, warm, sunny weather from June to September, around 25°C at its peak, raises afternoon ozone levels. Wildfire smoke is most likely from April to October, sometimes turning the sky hazy for days.
Are air quality levels in Pasadena, California based on measurements or forecasts?
It is forecasts derived by downscaling forecasts provided by EU’s Copernicus Atmosphere Monitoring Service (CAMS) by taking into account local conditions such as traffic patterns. CAMS bases its forecast on satellite measurements of particles and chemical compounds in the atmosphere. Airmine’s services were developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team.
Why doesn’t the forecast always reflect wildfire impacts?
Airmine’s forecast uses CAMS (Copernicus Atmosphere Monitoring Service) as its background atmospheric model. While CAMS includes wildfire emissions, these are derived from satellite observations and are not available in real time. During rapidly evolving wildfire events, there may therefore be a delay before increased emissions are incorporated into the model. As a result, the forecast may temporarily underestimate PM₂.₅ and other pollutants associated with wildfire smoke.
During rapidly evolving wildfire events, CAMS may lag by approximately 1–2 days before increased wildfire emissions are fully represented, which can lead to temporary underestimation of PM₂.₅ concentrations in Airmine’s forecast.
Understanding the Scale
The 0–100 air quality scores represent risk levels, not direct air pollutant concentrations. Higher scores indicate higher risk.
Air Quality
| Good | 0-20 | Low air quality risk. Air quality is expected to be good, with low levels of pollution. |
| Fair | 20-40 | Generally low air quality risk. Air quality is expected to be acceptable, with some pollution present. |
| Moderate | 40-60 | Moderate air quality risk. Air pollution is elevated and air quality may be less favorable. |
| Poor | 60-80 | High air quality risk. Air pollution is high and air quality is expected to be poor. |
| Very Poor | 80-100 | Very high air quality risk. Air pollution is very high and air quality is expected to be very poor. |