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Air quality · California, United States

San Diego Air Quality Index (AQI) today

Modelled estimate for 04:00 local time (UTC-8), refreshed 3 Nov, 07:52 UTC+0.

69 Moderate

Live estimate · modelled

US EPA AQI04:00 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 56.

Over the next 24 hours the model expects the AQI to range from 54 around 22:00 to 74 around 08:00 (3 Nov).

399th most polluted of 849 cities worldwide right now, 7th 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

05:00 · 51 06:00 · 49 07:00 · 49 08:00 · 48 09:00 · 44 10:00 · 37 11:00 · 34 12:00 · 35 13:00 · 38 14:00 · 41 15:00 · 43 16:00 · 44 17:00 · 47 18:00 · 53 19:00 · 56 20:00 · 60 21:00 · 63 22:00 · 65 23:00 · 66 00:00 · 67 01:00 · 68 02:00 · 69 03:00 · 69 04:00 · 69 05:00 · 69 06:00 · 70 07:00 · 72 08:00 · 74 09:00 · 73 10:00 · 72 11:00 · 71 12:00 · 70 13:00 · 68 14:00 · 66 15:00 · 65 16:00 · 64 17:00 · 63 18:00 · 61 19:00 · 59 20:00 · 57 21:00 · 55 22:00 · 54 23:00 · 55 00:00 · 58 01:00 · 63 02:00 · 65 03:00 · 67 04:00 · 68 05:00 · 68 06:00 · 68 07:00 · 68 08:00 · 67 09:00 · 66 10:00 · 61 11:00 · 56 12:00 · 54 13:00 · 53 14:00 · 52 15:00 · 52 16:00 · 53 17:00 · 54 18:00 · 56 19:00 · 59 20:00 · 63 21:00 · 67 22:00 · 71 23:00 · 74 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 05:0051
Mon 06:0049
Mon 07:0049
Mon 08:0048
Mon 09:0044
Mon 10:0037
Mon 11:0034
Mon 12:0035
Mon 13:0038
Mon 14:0041
Mon 15:0043
Mon 16:0044
Mon 17:0047
Mon 18:0053
Mon 19:0056
Mon 20:0060
Mon 21:0063
Mon 22:0065
Mon 23:0066
Tue 00:0067
Tue 01:0068
Tue 02:0069
Tue 03:0069
Tue 04:00 · Now69
Tue 05:00 · Forecast69
Tue 06:00 · Forecast70
Tue 07:00 · Forecast72
Tue 08:00 · Forecast74
Tue 09:00 · Forecast73
Tue 10:00 · Forecast72
Tue 11:00 · Forecast71
Tue 12:00 · Forecast70
Tue 13:00 · Forecast68
Tue 14:00 · Forecast66
Tue 15:00 · Forecast65
Tue 16:00 · Forecast64
Tue 17:00 · Forecast63
Tue 18:00 · Forecast61
Tue 19:00 · Forecast59
Tue 20:00 · Forecast57
Tue 21:00 · Forecast55
Tue 22:00 · Forecast54
Tue 23:00 · Forecast55
Wed 00:00 · Forecast58
Wed 01:00 · Forecast63
Wed 02:00 · Forecast65
Wed 03:00 · Forecast67
Wed 04:00 · Forecast68
Wed 05:00 · Forecast68
Wed 06:00 · Forecast68
Wed 07:00 · Forecast68
Wed 08:00 · Forecast67
Wed 09:00 · Forecast66
Wed 10:00 · Forecast61
Wed 11:00 · Forecast56
Wed 12:00 · Forecast54
Wed 13:00 · Forecast53
Wed 14:00 · Forecast52
Wed 15:00 · Forecast52
Wed 16:00 · Forecast53
Wed 17:00 · Forecast54
Wed 18:00 · Forecast56
Wed 19:00 · Forecast59
Wed 20:00 · Forecast63
Wed 21:00 · Forecast67
Wed 22:00 · Forecast71
Wed 23:00 · Forecast74

Pollutants this hour

  • PM2.5 18.7 µg/m³ 24-hour mean 12.0 µg/m³ · within WHO’s 24-hour guideline (15) 69
  • PM10 20 µg/m³ 18
  • O₃ 6 µg/m³ 4
  • NO₂ 42 µg/m³ 21
  • SO₂ 1 µg/m³ 0
  • CO 0.17 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
Tijuana Mexico 60
Mexicali Mexico 65
Los Angeles California 88
Phoenix Arizona 70
San Jose California 59
Hermosillo Mexico 16
San Francisco California 55

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 Diego’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 Diego right now?
69 on the US EPA scale (Moderate) at 04:00 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 Diego 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 Diego get better or worse tomorrow?
Over the next 24 hours the model expects the AQI to range from 54 around 22:00 to 74 around 08:00 (3 Nov). Forecasts beyond a day are less certain.

How does San Diego compare with other cities?
Right now it is the 399th most polluted of 849 cities we track worldwide, and 7th of 25 in United States, all on the same US EPA scale.

Why does another app show a different AQI for San Diego?
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.