Worst air pollution San Juan Capistrano, today and tomorrow

On 20 September 2026, overall air quality in San Juan Capistrano is moderate. AQI is the main air quality indicator at 43.1/100. Pollution peaks around 10:00 AM (PM10: 43.1/100).

On 21 September 2026, air quality conditions in San Juan Capistrano will be better than today, with AQI forecast at fair at 35.1/100. Pollution peaks around 2:00 AM (PM10: 35.1/100).

JSerra Catholic HS's Baseball Diamond's air quality follows a clear seasonal pattern: the cleanest air usually comes in winter, when storms periodically flush pollution out of the basin, but summer and early autumn bring the highest ozone levels, and wildfire smoke can spike particulate readings sharply from August through October. The mountains ringing the basin can trap pollution close to the ground for days when winds are calm.

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.

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.