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Air quality · California, United States

San Jose Air Quality Index (AQI) today

Modelled estimate for 03:00 local time (UTC-8), refreshed 3 Nov, 07:52 UTC+0.

58 Moderate

Live estimate · modelled

US EPA AQI03:00 UTC-8, 3 Nov Main pollutant: PM2.5

Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.

This page uses EPA’s NowCast, which follows the last few hours, as the US government’s AirNow does. On a 24-hour average of particles, as many apps show, it is 52.

Over the next 24 hours the model expects the AQI to range from 36 around 14:00 to 63 around 02:00 (4 Nov).

516th most polluted of 849 cities worldwide right now, 9th of 25 in United States.

What to do today

  • Long walk or run outside OK, lighter if very sensitive
  • Kids playing outside OK
  • Airing the house Open
  • Mask outdoors Not needed

Based on the US EPA’s health statement: “Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.” General guidance, not medical advice.

Last 24 hours and next 48

Past hours Forecast

04:00 · 62 05:00 · 62 06:00 · 61 07:00 · 61 08:00 · 59 09:00 · 54 10:00 · 41 11:00 · 29 12:00 · 24 13:00 · 28 14:00 · 32 15:00 · 37 16:00 · 41 17:00 · 42 18:00 · 40 19:00 · 45 20:00 · 51 21:00 · 54 22:00 · 57 23:00 · 58 00:00 · 59 01:00 · 59 02:00 · 58 03:00 · 58 04:00 · 59 05:00 · 60 06:00 · 61 07:00 · 62 08:00 · 61 09:00 · 57 10:00 · 52 11:00 · 49 12:00 · 46 13:00 · 39 14:00 · 36 15:00 · 36 16:00 · 39 17:00 · 39 18:00 · 42 19:00 · 48 20:00 · 52 21:00 · 54 22:00 · 56 23:00 · 58 00:00 · 60 01:00 · 62 02:00 · 63 03:00 · 62 04:00 · 61 05:00 · 60 06:00 · 59 07:00 · 60 08:00 · 60 09:00 · 60 10:00 · 58 11:00 · 55 12:00 · 52 13:00 · 48 14:00 · 47 15:00 · 47 16:00 · 48 17:00 · 49 18:00 · 49 19:00 · 49 20:00 · 48 21:00 · 47 22:00 · 47 23:00 · 47 Now

US EPA AQI per hour, UTC-8. Particles use EPA’s NowCast (a 12-hour weighted average), ozone and CO an 8-hour average. Lighter bars are the CAMS forecast.

Show as a table
TimeAQI
Mon 04:0062
Mon 05:0062
Mon 06:0061
Mon 07:0061
Mon 08:0059
Mon 09:0054
Mon 10:0041
Mon 11:0029
Mon 12:0024
Mon 13:0028
Mon 14:0032
Mon 15:0037
Mon 16:0041
Mon 17:0042
Mon 18:0040
Mon 19:0045
Mon 20:0051
Mon 21:0054
Mon 22:0057
Mon 23:0058
Tue 00:0059
Tue 01:0059
Tue 02:0058
Tue 03:00 · Now58
Tue 04:00 · Forecast59
Tue 05:00 · Forecast60
Tue 06:00 · Forecast61
Tue 07:00 · Forecast62
Tue 08:00 · Forecast61
Tue 09:00 · Forecast57
Tue 10:00 · Forecast52
Tue 11:00 · Forecast49
Tue 12:00 · Forecast46
Tue 13:00 · Forecast39
Tue 14:00 · Forecast36
Tue 15:00 · Forecast36
Tue 16:00 · Forecast39
Tue 17:00 · Forecast39
Tue 18:00 · Forecast42
Tue 19:00 · Forecast48
Tue 20:00 · Forecast52
Tue 21:00 · Forecast54
Tue 22:00 · Forecast56
Tue 23:00 · Forecast58
Wed 00:00 · Forecast60
Wed 01:00 · Forecast62
Wed 02:00 · Forecast63
Wed 03:00 · Forecast62
Wed 04:00 · Forecast61
Wed 05:00 · Forecast60
Wed 06:00 · Forecast59
Wed 07:00 · Forecast60
Wed 08:00 · Forecast60
Wed 09:00 · Forecast60
Wed 10:00 · Forecast58
Wed 11:00 · Forecast55
Wed 12:00 · Forecast52
Wed 13:00 · Forecast48
Wed 14:00 · Forecast47
Wed 15:00 · Forecast47
Wed 16:00 · Forecast48
Wed 17:00 · Forecast49
Wed 18:00 · Forecast49
Wed 19:00 · Forecast49
Wed 20:00 · Forecast48
Wed 21:00 · Forecast47
Wed 22:00 · Forecast47
Wed 23:00 · Forecast47

Pollutants this hour

  • PM2.5 13.1 µg/m³ 24-hour mean 9.8 µg/m³ · within WHO’s 24-hour guideline (15) 58
  • PM10 17 µg/m³ 15
  • O₃ 36 µg/m³ 13
  • NO₂ 22 µg/m³ 10
  • SO₂ 1 µg/m³ 0
  • CO 0.20 mg/m³ 2

Modelled concentrations at the city’s location (CAMS). The sub-index uses the same averaging as the headline, so the highest one is the AQI.

Nearby cities

City AQI
San Francisco California 56
Los Angeles California 88
San Diego California 69
Tijuana Mexico 58
Mexicali Mexico 66
Portland Oregon 76
Phoenix Arizona 74

Where this number comes from

The Copernicus Atmosphere Monitoring Service (CAMS) forecasts air pollution worldwide on a grid (about 11 km over Europe, about 45 km elsewhere). We take the grid value at San Jose’s coordinates and score it with the US EPA’s method. It is a model, not a measurement: a nearby monitoring station can read quite differently, especially next to busy roads or during fires and dust storms.

Full methodology · Data: CAMS via Open-Meteo (CC BY 4.0); city list: GeoNames (CC BY 4.0).

  • Good 0–50
  • Moderate 51–100
  • Unhealthy for sensitive groups 101–150
  • Unhealthy 151–200
  • Very unhealthy 201–300
  • Hazardous 301–500

Questions

What is the AQI in San Jose right now?
58 on the US EPA scale (Moderate) at 03:00 UTC-8, 3 Nov. PM2.5 is the pollutant with the highest sub-index. This is a modelled estimate from the Copernicus Atmosphere Monitoring Service (CAMS), not a reading from a monitoring station.

Is it safe to exercise outside in San Jose today?
For most people, yes. The EPA’s statement for “Moderate”: Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution. General guidance, not medical advice.

Will the air in San Jose get better or worse tomorrow?
Over the next 24 hours the model expects the AQI to range from 36 around 14:00 to 63 around 02:00 (4 Nov). Forecasts beyond a day are less certain.

How does San Jose compare with other cities?
Right now it is the 516th most polluted of 849 cities we track worldwide, and 9th of 25 in United States, all on the same US EPA scale.

Why does another app show a different AQI for San Jose?
Apps differ in source (government stations, low-cost sensors or a model like this one), in scale (US EPA, European, or a national index) and in averaging (hourly or NowCast, 8-hour, 24-hour). This page uses the US EPA AQI with EPA’s NowCast for particles, computed from the CAMS forecast for the city’s location.