Worst air pollution Half Moon Bay, today and tomorrow
Today (15 July): Air quality in Half Moon Bay is fair. AQI and O3 are fair; PM2.5, PM10, NO2, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 8:00 AM (O3: 39.4/100).
Tomorrow (16 July 2026): Air quality in Half Moon Bay is medium. AQI improves to medium; O3 decreases to medium; all other pollutants stay as today. Pollution peaks around 10:00 AM (O3: 41.0/100). 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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Air quality in Half Moon Bay is driven mostly by cool Pacific fog — marine fog and onshore breeze keep pollutant levels low year-round. These factors combine to give Half Moon Bay a fairly typical seasonal air quality pattern for this part of the country. Local topography and prevailing winds both play a role in how quickly conditions change.
Today - 15 July | Pollution peaks at 08:00
AQI:
Fair
39.4/100
PM2.5 (fine particles):
Good
13.4/100
PM10 (coarse particles):
Good
8.2/100
NO2 (nitrogen dioxide):
Good
3.9/100
O3 (ozone):
Fair
39.4/100
SO2 (sulfur dioxide):
Good
1.7/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
2.2/100
PM1 (ultrafine particles):
Good
7.3/100
Levels show the poorest local air quality during the day
Tomorrow - 16 July | Pollution peaks at 10:00
AQI:
Medium
41.0/100
PM2.5 (fine particles):
Good
18.6/100
PM10 (coarse particles):
Good
9.0/100
NO2 (nitrogen dioxide):
Good
8.4/100
O3 (ozone):
Medium
41.0/100
SO2 (sulfur dioxide):
Good
1.7/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
1.9/100
PM1 (ultrafine particles):
Good
12.2/100
Pollen forecast in Half Moon Bay
View pollen forecastFrequently Asked Questions
Is air quality bad in Half Moon Bay right now?
On 15 July 2026, overall air quality in Half Moon Bay is fair. AQI is the main air quality indicator at 39.4/100. Pollution peaks around 8:00 AM (O3: 39.4/100).
Will air quality be worse tomorrow in Half Moon Bay?
On 16 July 2026, air quality conditions in Half Moon Bay will be better than today, with AQI forecast at medium at 41.0/100. Pollution peaks around 10:00 AM (O3: 41.0/100).
When is air pollution at its worst in Half Moon Bay?
Seasonal changes shape air quality across Half Moon Bay — winter rains provide the only real relief from an otherwise persistent haze, 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 Half Moon Bay 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.
Want to see air quality forecasts for other cities in United States?
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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