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

Today (16 July): Air quality in San Sebastián de los Reyes is fair. AQI and O3 are fair; PM2.5, PM10, NO2, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 3:00 PM (O3: 36.2/100).
Tomorrow (17 July 2026): Air quality in San Sebastián de los Reyes is fair. All pollutants stay as today. Pollution peaks around 3:00 PM (O3: 38.9/100). Airmine updates local air quality forecasts four times daily.

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Developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team

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San Sebastián de los Reyes' air quality reflects the northern Madrid metropolitan technology corridor, with vehicle traffic on the A-1 motorway and surrounding retail and automotive dealership operations contributing elevated NOₓ. The Madrid basin's winter temperature inversion affects the northern corridor, while the flat Castilian Meseta north of Madrid provides some dispersal on northerly wind days throughout the year.

Today - 16 July | Pollution peaks at 15:00

AQI:

Fair

36.2/100

PM2.5 (fine particles):

Good

10.7/100

PM10 (coarse particles):

Good

8.7/100

NO2 (nitrogen dioxide):

Good

7.8/100

O3 (ozone):

Fair

36.2/100

SO2 (sulfur dioxide):

Good

1.6/100

CO (carbon monoxide):

Good

0.0/100

HCHO (formaldehyde):

Good

7.2/100

PM1 (ultrafine particles):

Good

7.4/100

Levels show the poorest local air quality during the day

Tomorrow - 17 July | Pollution peaks at 15:00

AQI:

Fair

38.9/100

PM2.5 (fine particles):

Good

9.3/100

PM10 (coarse particles):

Good

5.1/100

NO2 (nitrogen dioxide):

Good

7.8/100

O3 (ozone):

Fair

38.9/100

SO2 (sulfur dioxide):

Good

1.0/100

CO (carbon monoxide):

Good

0.0/100

HCHO (formaldehyde):

Good

7.7/100

PM1 (ultrafine particles):

Good

5.4/100

Pollen forecast in San Sebastián de los Reyes

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Frequently Asked Questions

Is air quality bad in San Sebastián de los Reyes right now?

On 16 July 2026, overall air quality in San Sebastián de los Reyes is fair. AQI is the main air quality indicator at 36.2/100. Pollution peaks around 3:00 PM (O3: 36.2/100).

Will air quality be worse tomorrow in San Sebastián de los Reyes?

On 17 July 2026, air quality conditions in San Sebastián de los Reyes will be similar to today, with AQI forecast at fair at 38.9/100. Pollution peaks around 3:00 PM (O3: 38.9/100).

When is air pollution at its worst in San Sebastián de los Reyes?

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.

Are air quality levels in San Sebastián de los Reyes 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.

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Data provided by Airmine — Last update: 16 July 2026 at 10:33 CEST (Data is updated four times daily.)

This forecast is produced independently using Airmine's own atmospheric data and models.

Unless explicitly made clear, the content on this site has not been paid for by external organisations and is Airmine's sole responsibility.

For long term forecasts and maps, see the Airmine app