Worst air pollution El Cajon, today and tomorrow
Today (20 September): Air quality in El Cajon is moderate. AQI, PM2.5, and PM10 are moderate; NO2 is fair; O3, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 10:00 AM (PM10: 50.1/100).
Tomorrow (21 September 2026): Air quality in El Cajon is moderate. PM2.5 decreases to fair; NO2 decreases to good; all other pollutants stay as today. Pollution peaks around 9:00 AM (PM10: 42.6/100). Airmine updates local air quality forecasts four times daily.
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El Cajon's air quality reflects the San Diego County inland valley position, with vehicle emissions from SR-8 and the surrounding urban commercial character creating warmer, more stagnant conditions than the coastal San Diego suburbs. The surrounding Cuyamaca Mountains and Viejas Ridge create topographic enclosure, while the valley position means El Cajon experiences higher ozone concentrations than coastal San Diego and occasional Santa Ana wind events can worsen conditions.
Today - 20 September | Pollution peaks at 10:00
AQI:
Moderate
50.1/100
PM2.5 (fine particles):
Moderate
40.8/100
PM10 (coarse particles):
Moderate
50.1/100
NO2 (nitrogen dioxide):
Fair
28.1/100
O3 (ozone):
Good
13.3/100
SO2 (sulfur dioxide):
Good
0.3/100
CO (carbon monoxide):
Good
0.4/100
HCHO (formaldehyde):
Good
1.2/100
PM1 (ultrafine particles):
Good
10.7/100
Levels show the poorest local air quality during the day
Tomorrow - 21 September | Pollution peaks at 09:00
AQI:
Moderate
42.6/100
PM2.5 (fine particles):
Fair
39.0/100
PM10 (coarse particles):
Moderate
42.6/100
NO2 (nitrogen dioxide):
Good
15.2/100
O3 (ozone):
Good
14.8/100
SO2 (sulfur dioxide):
Good
0.3/100
CO (carbon monoxide):
Good
0.4/100
HCHO (formaldehyde):
Good
1.1/100
PM1 (ultrafine particles):
Good
16.1/100
Pollen forecast in El Cajon
View pollen forecastAir quality forecasts for neighbourhoods and landmarks in El Cajon
Frequently Asked Questions
Is air quality bad in El Cajon right now?
On 20 September 2026, overall air quality in El Cajon is moderate. AQI is the main air quality indicator at 50.1/100. Pollution peaks around 10:00 AM (PM10: 50.1/100).
Will air quality be worse tomorrow in El Cajon?
On 21 September 2026, air quality conditions in El Cajon will be similar to today, with AQI forecast at moderate at 42.6/100. Pollution peaks around 9:00 AM (PM10: 42.6/100).
When is air pollution at its worst in El Cajon?
El Cajon experiences a distinct seasonal swing in air quality — the shortest stretch of clean air usually falls in the wetter winter months, whereas summer sunshine and heat drive some of the worst ozone readings in the country. The mountains ringing the basin can trap pollution close to the ground for days when winds are calm.
Are air quality levels in El Cajon 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.
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Data provided by Airmine — Last update: 20 September 2026 at 14:33 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.
Disclaimer: Forecasts are provided for informational purposes only and should not be relied upon as medical advice. Actual pollen and air quality conditions may vary from the forecast. If you have allergies, asthma, or another medical condition, consult a healthcare professional. Please see our Terms of Service for important information about limitations of liability.
Some text on this page may be generated or summarised using artificial intelligence (AI). Wherever possible, AI-generated content is enriched with Airmine's proprietary data to improve its accuracy and relevance. However, AI-generated content may still contain errors, omissions, or inaccuracies.
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