Worst air pollution San Sebastián de los Reyes, today and tomorrow

On 9 August 2026, overall air quality in San Sebastián de los Reyes is fair. AQI is the main air quality indicator at 34.2/100. Pollution peaks around 3:00 PM (O3: 34.2/100).

On 10 August 2026, air quality conditions in San Sebastián de los Reyes will be similar to today, with AQI forecast at fair at 35.6/100. Pollution peaks around 4:00 PM (O3: 35.6/100).

What time of year has the cleanest air in San Sebastián de los Reyes? Air quality is typically at its weakest in December and January, when cold, calm high-pressure spells trap traffic exhaust and wood-smoke close to the ground instead of letting it disperse. Spring usually brings an improvement as more frequent rain and stronger winds help clear the air and wash out pollutants that built up over winter. Hot, stagnant summer air favours ozone formation, and dry vegetation nearby occasionally adds wildfire smoke to the mix during peak heat. The transition into autumn generally brings cleaner conditions, as more frequent rainfall and lower temperatures curb ozone formation. The interior's dry continental climate means winter inversions and summer heat both tend to hit harder than along the coast.

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.