Worst air pollution West Portal - San Francisco, today and tomorrow
Today (20 September): Air quality in West Portal is moderate. AQI and O3 are moderate; PM2.5 is fair; PM10, NO2, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 11:00 PM (O3: 55.1/100).
Tomorrow (21 September 2026): Air quality in West Portal is moderate. PM10 increases to fair; all other pollutants stay as today. Pollution peaks around 1:00 AM (O3: 57.3/100). Airmine updates local air quality forecasts four times daily.
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In West Portal, quieter roads here mean surrounding agricultural activity, more than congestion, tends to shape local particulate levels. Some of this load is absorbed by nearby vegetation, acting as a modest natural filter. Actual air quality on a given day still depends heavily on local wind and weather conditions.
Today - 20 September | Pollution peaks at 23:00
AQI:
Moderate
55.1/100
PM2.5 (fine particles):
Fair
20.3/100
PM10 (coarse particles):
Good
19.4/100
NO2 (nitrogen dioxide):
Good
2.1/100
O3 (ozone):
Moderate
55.1/100
SO2 (sulfur dioxide):
Good
0.5/100
CO (carbon monoxide):
Good
0.5/100
HCHO (formaldehyde):
Good
1.3/100
PM1 (ultrafine particles):
Good
15.4/100
Levels show the poorest local air quality during the day
Tomorrow - 21 September | Pollution peaks at 01:00
AQI:
Moderate
57.3/100
PM2.5 (fine particles):
Fair
24.0/100
PM10 (coarse particles):
Fair
21.9/100
NO2 (nitrogen dioxide):
Good
1.6/100
O3 (ozone):
Moderate
57.3/100
SO2 (sulfur dioxide):
Good
0.6/100
CO (carbon monoxide):
Good
0.5/100
HCHO (formaldehyde):
Good
1.2/100
PM1 (ultrafine particles):
Good
17.6/100
Other Landmarks in San Francisco
Sports venues in San Francisco
Frequently Asked Questions
Is air quality bad in West Portal right now?
On 20 September 2026, overall air quality in West Portal is moderate. AQI is the main air quality indicator at 55.1/100. Pollution peaks around 11:00 PM (O3: 55.1/100).
Will air quality be worse tomorrow in West Portal?
On 21 September 2026, air quality conditions in West Portal will be similar to today, with AQI forecast at moderate at 57.3/100. Pollution peaks around 1:00 AM (O3: 57.3/100).
When is air pollution at its worst in West Portal?
From November to January, average wind speeds run around 15 km/h with temperatures near 12°C, calm and cool enough to let particulate matter and smoke build up near the ground rather than disperse. From August to October, temperatures average around 16°C, warm enough for strong sun and heat to drive ground-level ozone formation.
Are air quality levels in West Portal 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 20:27 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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