Worst air pollution Hornsby - Sydney, today and tomorrow
Today (4 August): Air quality in Hornsby is fair. AQI, NO2, and O3 are fair; PM2.5, PM10, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 7:00 PM (NO2: 31.6/100).
Tomorrow (5 August 2026): Air quality in Hornsby is fair. O3 decreases to good; all other pollutants stay as today. Pollution peaks around 7:00 PM (NO2: 34.4/100). Airmine updates local air quality forecasts four times daily.
For long term forecasts and maps, see the Airmine app
Developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team
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Hornsby sits on an elevated ridge on Sydney's Upper North Shore, surrounded by extensive bushland reserves, a setting that supports generally good air movement despite fairly busy traffic along the Pacific Highway and rail corridor through the town centre. This bushland proximity makes Hornsby more exposed to bushfire smoke in dry summers than harbourside suburbs closer to the water. There is no industry here. Overall, background air quality is good, balancing traffic through the centre against extensive surrounding green space.
Today - 4 August | Pollution peaks at 19:00
AQI:
Fair
31.6/100
PM2.5 (fine particles):
Good
7.6/100
PM10 (coarse particles):
Good
2.3/100
NO2 (nitrogen dioxide):
Fair
31.6/100
O3 (ozone):
Fair
20.3/100
SO2 (sulfur dioxide):
Good
7.1/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
4.8/100
PM1 (ultrafine particles):
Good
9.2/100
Levels show the poorest local air quality during the day
Tomorrow - 5 August | Pollution peaks at 19:00
AQI:
Fair
34.4/100
PM2.5 (fine particles):
Good
7.2/100
PM10 (coarse particles):
Good
2.0/100
NO2 (nitrogen dioxide):
Fair
34.4/100
O3 (ozone):
Good
18.6/100
SO2 (sulfur dioxide):
Good
7.0/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
4.3/100
PM1 (ultrafine particles):
Good
9.7/100
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Frequently Asked Questions
Is air quality bad in Hornsby right now?
On 4 August 2026, overall air quality in Hornsby is fair. AQI is the main air quality indicator at 31.6/100. Pollution peaks around 7:00 PM (NO2: 31.6/100).
Will air quality be worse tomorrow in Hornsby?
On 5 August 2026, air quality conditions in Hornsby will be similar to today, with AQI forecast at fair at 34.4/100. Pollution peaks around 7:00 PM (NO2: 34.4/100).
When is air pollution at its worst in Hornsby?
On Sydney's bushy upper north shore, Hornsby sits closer to extensive bushland than most suburbs, making it more exposed to summer bushfire smoke (December–March) when fires burn nearby. Cold winter nights bring a mild wood-heater haze in this leafy area. Expect sharper seasonal dips here than in harbourside Sydney.
Are air quality levels in Hornsby 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: 4 August 2026 at 16:38 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.
For long term forecasts and maps, see the Airmine app