San Luis Obispo Air Quality Forecast - Today, Tomorrow
Air Quality Today
Today (10 October): Air quality in San Luis Obispo is moderate. AQI and NO2 are moderate; PM2.5 and O3 are fair; PM10, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 4:00 PM (NO2: 45.5/100).
Air Quality Tomorrow
Tomorrow (11 October 2026): Air quality in San Luis Obispo is poor. AQI worsens to poor; NO2 increases to poor; PM1 increases to fair; all other pollutants stay as today. Pollution peaks around 3:00 PM (NO2: 61.5/100).
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Air Quality
Today - 10 October
| Pollutant | Level | Value |
|---|---|---|
| AQI | Moderate | 45.5/100 |
| PM2.5 (fine particles) | Fair | 24.3/100 |
| PM10 (coarse particles) | Good | 18.4/100 |
| NO2 (nitrogen dioxide) | Moderate | 45.5/100 |
| O3 (ozone) | Fair | 33.8/100 |
| SO2 (sulfur dioxide) | Good | 1.5/100 |
| CO (carbon monoxide) | Good | 0.6/100 |
| HCHO (formaldehyde) | Good | 1.7/100 |
| PM1 (ultrafine particles) | Good | 17.3/100 |
Tomorrow - 11 October
| Pollutant | Level | Value |
|---|---|---|
| AQI | Poor | 61.5/100 |
| PM2.5 (fine particles) | Fair | 32.0/100 |
| PM10 (coarse particles) | Good | 19.3/100 |
| NO2 (nitrogen dioxide) | Poor | 61.5/100 |
| O3 (ozone) | Fair | 37.2/100 |
| SO2 (sulfur dioxide) | Good | 2.6/100 |
| CO (carbon monoxide) | Good | 0.6/100 |
| HCHO (formaldehyde) | Good | 2.7/100 |
| PM1 (ultrafine particles) | Fair | 27.2/100 |
Local Environmental Conditions
Around the heart of San Luis Obispo, dense development means road traffic is the main local source of nitrogen dioxide and fine particles. Pockets of trees and green space help filter a small share of the particles from traffic. On some days, pollution drifting in from farther away outweighs local sources.
Ozone is the main concern from June to September, when sunny days averaging 22°C turn traffic and other emissions into ozone by mid-afternoon. Cold spells from December to February, at around 10°C on average, are when smoke from home heating and traffic lingers longest. From one day to the next, still, dry weather allows pollution to accumulate, and wind or rain clears it out.
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Frequently Asked Questions About Air Quality in California
Is air quality bad in San Luis Obispo right now?
On 10 October 2026, overall air quality in San Luis Obispo is moderate. AQI is the main air quality indicator at 45.5/100. Pollution peaks around 4:00 PM (NO2: 45.5/100).
Will air quality be worse tomorrow in San Luis Obispo?
On 11 October 2026, air quality conditions in San Luis Obispo will be worse than today, with AQI forecast at poor at 61.5/100. Pollution peaks around 3:00 PM (NO2: 61.5/100).
When is air pollution at its worst in San Luis Obispo?
Ozone is the main concern from June to September, when sunny days averaging 22°C turn traffic and other emissions into ozone by mid-afternoon. Cold spells from December to February, at around 10°C on average, are when smoke from home heating and traffic lingers longest. From one day to the next, still, dry weather allows pollution to accumulate, and wind or rain clears it out.
Are air quality levels in San Luis Obispo 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. |