Worst air pollution Castro Valley, today and tomorrow
Today (9 August): Air quality in Castro Valley is fair. AQI and O3 are fair; PM2.5, PM10, NO2, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 6:00 AM (O3: 30.1/100).
Tomorrow (10 August 2026): Air quality in Castro Valley is fair. All pollutants stay as today. Pollution peaks around 11:00 PM (O3: 34.8/100). 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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Castro Valley's air quality reflects the East Bay's unincorporated Alameda County position in the San Lorenzo creek valley, with vehicle emissions from I-580 the primary local source. The Bay Delta breeze provides afternoon ventilation, while the surrounding East Bay Regional Parklands hills create topographic variation and summer wildfire smoke from the surrounding Diablo Range and chaparral hills is an increasingly frequent and severe seasonal air quality concern throughout the year.
Today - 9 August | Pollution peaks at 06:00
AQI:
Fair
30.1/100
PM2.5 (fine particles):
Good
11.0/100
PM10 (coarse particles):
Good
4.2/100
NO2 (nitrogen dioxide):
Good
0.9/100
O3 (ozone):
Fair
30.1/100
SO2 (sulfur dioxide):
Good
0.6/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
1.8/100
PM1 (ultrafine particles):
Good
7.2/100
Levels show the poorest local air quality during the day
Tomorrow - 10 August | Pollution peaks at 23:00
AQI:
Fair
34.8/100
PM2.5 (fine particles):
Good
9.6/100
PM10 (coarse particles):
Good
4.4/100
NO2 (nitrogen dioxide):
Good
0.5/100
O3 (ozone):
Fair
34.8/100
SO2 (sulfur dioxide):
Good
0.5/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
2.0/100
PM1 (ultrafine particles):
Good
6.4/100
Pollen forecast in Castro Valley
View pollen forecastFrequently Asked Questions
Is air quality bad in Castro Valley right now?
On 9 August 2026, overall air quality in Castro Valley is fair. AQI is the main air quality indicator at 30.1/100. Pollution peaks around 6:00 AM (O3: 30.1/100).
Will air quality be worse tomorrow in Castro Valley?
On 10 August 2026, air quality conditions in Castro Valley will be similar to today, with AQI forecast at fair at 34.8/100. Pollution peaks around 11:00 PM (O3: 34.8/100).
When is air pollution at its worst in Castro Valley?
Seasonal changes shape air quality across Castro Valley. Typically, winter typically brings the cleanest stretch, once occasional rain clears the basin, while hot, sunny summer conditions drive persistent ozone problems, compounded by wildfire smoke risk into early autumn. The mountains ringing the basin can trap pollution close to the ground for days when winds are calm.
Are air quality levels in Castro Valley 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: 9 August 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.
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