Worst air pollution Semaphore - Adelaide, today and tomorrow
Today (17 September): Air quality in Semaphore is fair. AQI and PM2.5 are fair; PM10, NO2, O3, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 9:30 PM (PM2.5: 37.2/100).
Tomorrow (18 September 2026): Air quality in Semaphore is fair. All pollutants stay as today. Pollution peaks around 12:30 AM (PM2.5: 24.4/100). Airmine updates local air quality forecasts four times daily.
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Semaphore sits directly on the Adelaide coast, its beachside position capturing the reliable Gulf St Vincent sea breeze that keeps background air quality generally excellent. Its proximity to Port Adelaide's industrial and shipping precinct just inland means the suburb can occasionally pick up drift from that activity under certain wind conditions, a distinctive factor not shared by other Adelaide beach suburbs. Bushfire smoke is a periodic summer risk from the Adelaide Hills. Overall, coastal exposure keeps conditions generally clean.
Today - 17 September | Pollution peaks at 21:30
AQI:
Fair
37.2/100
PM2.5 (fine particles):
Fair
37.2/100
PM10 (coarse particles):
Good
18.9/100
NO2 (nitrogen dioxide):
Good
16.2/100
O3 (ozone):
Good
13.5/100
SO2 (sulfur dioxide):
Good
2.1/100
CO (carbon monoxide):
Good
0.5/100
HCHO (formaldehyde):
Good
2.5/100
PM1 (ultrafine particles):
Good
12.6/100
Levels show the poorest local air quality during the day
Tomorrow - 18 September | Pollution peaks at 00:30
AQI:
Fair
24.4/100
PM2.5 (fine particles):
Fair
24.4/100
PM10 (coarse particles):
Good
11.0/100
NO2 (nitrogen dioxide):
Good
17.7/100
O3 (ozone):
Good
13.3/100
SO2 (sulfur dioxide):
Good
1.8/100
CO (carbon monoxide):
Good
0.5/100
HCHO (formaldehyde):
Good
2.7/100
PM1 (ultrafine particles):
Good
8.4/100
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Frequently Asked Questions
Is air quality bad in Semaphore right now?
On 17 September 2026, overall air quality in Semaphore is fair. AQI is the main air quality indicator at 37.2/100. Pollution peaks around 9:30 PM (PM2.5: 37.2/100).
Will air quality be worse tomorrow in Semaphore?
On 18 September 2026, air quality conditions in Semaphore will be similar to today, with AQI forecast at fair at 24.4/100. Pollution peaks around 12:30 AM (PM2.5: 24.4/100).
When is air pollution at its worst in Semaphore?
As a beachside suburb, Semaphore benefits from consistent sea breezes that keep air quality high for most of the year. The exception is summer, December to March, when bushfire smoke, usually originating from the Adelaide Hills or further inland, can occasionally drift over on hot, calm mornings before the sea breeze clears it. Otherwise, expect clean coastal air.
Are air quality levels in Semaphore 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: 16 September 2026 at 20:30 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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