Japantown San Jose, San Jose Air Quality Forecast - Today, Tomorrow
Air Quality Today
Today (10 October): Air quality in Japantown San Jose is fair. AQI, PM2.5, and O3 are fair; PM10, NO2, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 2:00 AM (O3: 27.7/100).
Air Quality Tomorrow
Tomorrow (11 October 2026): Air quality in Japantown San Jose is fair. PM10 increases to fair; all other pollutants stay as today. Pollution peaks around 3:00 PM (PM2.5: 33.4/100).
Explore Forecasts
Pollen & Mold
Air Quality for Neighborhoods
Get More in Our App
Local pollen and air quality forecasts, interactive pollen maps and route profiles
Features and forecast availability vary by region.
Air Quality
Today - 10 October
| Pollutant | Level | Value |
|---|---|---|
| AQI | Fair | 27.7/100 |
| PM2.5 (fine particles) | Fair | 24.9/100 |
| PM10 (coarse particles) | Good | 16.3/100 |
| NO2 (nitrogen dioxide) | Good | 6.7/100 |
| O3 (ozone) | Fair | 27.7/100 |
| SO2 (sulfur dioxide) | Good | 0.5/100 |
| CO (carbon monoxide) | Good | 0.5/100 |
| HCHO (formaldehyde) | Good | 1.1/100 |
| PM1 (ultrafine particles) | Good | 9.5/100 |
Tomorrow - 11 October
| Pollutant | Level | Value |
|---|---|---|
| AQI | Fair | 33.4/100 |
| PM2.5 (fine particles) | Fair | 33.4/100 |
| PM10 (coarse particles) | Fair | 21.0/100 |
| NO2 (nitrogen dioxide) | Good | 10.0/100 |
| O3 (ozone) | Fair | 29.3/100 |
| SO2 (sulfur dioxide) | Good | 0.9/100 |
| CO (carbon monoxide) | Good | 0.5/100 |
| HCHO (formaldehyde) | Good | 1.6/100 |
| PM1 (ultrafine particles) | Good | 17.9/100 |
Local Environmental Conditions
With buildings covering much of the area around this site in San Jose, traffic and other urban emissions are the biggest local influence on air quality. On the Bay Delta, pollution from the wider region can build up over large areas when winds are light. Pockets of trees and green space help filter a small share of the particles from traffic.
Fine particle levels climb from December to February, as home heating and traffic combine with cold, still air averaging 9°C. By contrast, summer sun in August cooks traffic fumes into ozone, especially in the warmest month, which averages 20°C. June is usually the windiest month, averaging about 15 km/h, which helps keep the air clean.
Get pollen & AQ on Strava
Follow your environmental exposure and performance with the free Airmine-Strava integration. See your pollen and air quality exposure for every Strava activity.
Resource Hub
Air quality forecast neighborhoods 80 neighborhoods
Sports venues in San Jose 1 sports venue
Frequently Asked Questions About Air Quality in California
Is air quality bad in Japantown San Jose right now?
On 10 October 2026, overall air quality in Japantown San Jose is fair. AQI is the main air quality indicator at 27.7/100. Pollution peaks around 2:00 AM (O3: 27.7/100).
Will air quality be worse tomorrow in Japantown San Jose?
On 11 October 2026, air quality conditions in Japantown San Jose will be similar to today, with AQI forecast at fair at 33.4/100. Pollution peaks around 3:00 PM (PM2.5: 33.4/100).
When is air pollution at its worst in Japantown San Jose?
Fine particle levels climb from December to February, as home heating and traffic combine with cold, still air averaging 9°C. By contrast, summer sun in August cooks traffic fumes into ozone, especially in the warmest month, which averages 20°C. June is usually the windiest month, averaging about 15 km/h, which helps keep the air clean.
Are air quality levels in Japantown San Jose 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.
Understanding the Scale
The 0–100 air quality scores represent risk levels, not direct air pollutant concentrations. Higher scores indicate higher risk.
Air Quality
| Good | 0-20 | Low air quality risk. Air quality is expected to be good, with low levels of pollution. |
| Fair | 20-40 | Generally low air quality risk. Air quality is expected to be acceptable, with some pollution present. |
| Moderate | 40-60 | Moderate air quality risk. Air pollution is elevated and air quality may be less favorable. |
| Poor | 60-80 | High air quality risk. Air pollution is high and air quality is expected to be poor. |
| Very Poor | 80-100 | Very high air quality risk. Air pollution is very high and air quality is expected to be very poor. |