Worst air pollution Porthmadog, today and tomorrow
Today (16 July): Air quality in Porthmadog is fair. AQI and O3 are fair; PM2.5, PM10, NO2, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 2:00 PM (O3: 28.5/100).
Tomorrow (17 July 2026): Air quality in Porthmadog is fair. All pollutants stay as today. Pollution peaks around 3:00 PM (O3: 31.9/100). 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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Like much of Gwynedd, Porthmadog's air quality is shaped less by industry these days and more by everyday road traffic. The A470 sees the heaviest traffic, and that shows up clearly in local roadside monitoring. Southwesterly winds do most of the work keeping things in check, more so than any local policy or infrastructure change.
Today - 16 July | Pollution peaks at 14:00
AQI:
Fair
28.5/100
PM2.5 (fine particles):
Good
10.6/100
PM10 (coarse particles):
Good
3.7/100
NO2 (nitrogen dioxide):
Good
9.5/100
O3 (ozone):
Fair
28.5/100
SO2 (sulfur dioxide):
Good
2.1/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
2.1/100
PM1 (ultrafine particles):
Good
8.4/100
Levels show the poorest local air quality during the day
Tomorrow - 17 July | Pollution peaks at 15:00
AQI:
Fair
31.9/100
PM2.5 (fine particles):
Good
14.9/100
PM10 (coarse particles):
Good
5.3/100
NO2 (nitrogen dioxide):
Good
13.3/100
O3 (ozone):
Fair
31.9/100
SO2 (sulfur dioxide):
Good
3.9/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
3.1/100
PM1 (ultrafine particles):
Good
12.3/100
Pollen forecast in Porthmadog
View pollen forecastFrequently Asked Questions
Is air quality bad in Porthmadog right now?
On 16 July 2026, overall air quality in Porthmadog is fair. AQI is the main air quality indicator at 28.5/100. Pollution peaks around 2:00 PM (O3: 28.5/100).
Will air quality be worse tomorrow in Porthmadog?
On 17 July 2026, air quality conditions in Porthmadog will be similar to today, with AQI forecast at fair at 31.9/100. Pollution peaks around 3:00 PM (O3: 31.9/100).
When is air pollution at its worst in Porthmadog?
In Porthmadog, pollution levels don't stay flat — winter and summer look pretty different. Winter mornings can be the trickiest, with cold, still conditions trapping A470 traffic fumes and smoke from home fires close to the ground. Warmer months swap one problem for another — less smoke and heating pollution, but more ozone on the sunniest days. Most of spring and autumn stays fairly steady, right in the middle of those two extremes.
Are air quality levels in Porthmadog 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