Air quality · California, United States
San Francisco Air Quality Index (AQI) today
Modelled estimate for 04:00 local time (UTC-8), refreshed 3 Nov, 07:52 UTC+0.
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 54.
Over the next 24 hours the model expects the AQI to range from 47 around 12:00 to 56 around 20:00 (3 Nov).
583rd most polluted of 849 cities worldwide right now, 11th 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
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
| Time | AQI |
|---|---|
| Mon 05:00 | 50 |
| Mon 06:00 | 51 |
| Mon 07:00 | 52 |
| Mon 08:00 | 52 |
| Mon 09:00 | 52 |
| Mon 10:00 | 52 |
| Mon 11:00 | 51 |
| Mon 12:00 | 51 |
| Mon 13:00 | 51 |
| Mon 14:00 | 51 |
| Mon 15:00 | 51 |
| Mon 16:00 | 51 |
| Mon 17:00 | 52 |
| Mon 18:00 | 52 |
| Mon 19:00 | 52 |
| Mon 20:00 | 53 |
| Mon 21:00 | 55 |
| Mon 22:00 | 56 |
| Mon 23:00 | 58 |
| Tue 00:00 | 58 |
| Tue 01:00 | 58 |
| Tue 02:00 | 57 |
| Tue 03:00 | 56 |
| Tue 04:00 · Now | 55 |
| Tue 05:00 · Forecast | 53 |
| Tue 06:00 · Forecast | 52 |
| Tue 07:00 · Forecast | 52 |
| Tue 08:00 · Forecast | 52 |
| Tue 09:00 · Forecast | 52 |
| Tue 10:00 · Forecast | 51 |
| Tue 11:00 · Forecast | 48 |
| Tue 12:00 · Forecast | 47 |
| Tue 13:00 · Forecast | 47 |
| Tue 14:00 · Forecast | 48 |
| Tue 15:00 · Forecast | 49 |
| Tue 16:00 · Forecast | 51 |
| Tue 17:00 · Forecast | 52 |
| Tue 18:00 · Forecast | 54 |
| Tue 19:00 · Forecast | 55 |
| Tue 20:00 · Forecast | 56 |
| Tue 21:00 · Forecast | 56 |
| Tue 22:00 · Forecast | 56 |
| Tue 23:00 · Forecast | 56 |
| Wed 00:00 · Forecast | 55 |
| Wed 01:00 · Forecast | 56 |
| Wed 02:00 · Forecast | 56 |
| Wed 03:00 · Forecast | 56 |
| Wed 04:00 · Forecast | 56 |
| Wed 05:00 · Forecast | 56 |
| Wed 06:00 · Forecast | 57 |
| Wed 07:00 · Forecast | 58 |
| Wed 08:00 · Forecast | 60 |
| Wed 09:00 · Forecast | 61 |
| Wed 10:00 · Forecast | 60 |
| Wed 11:00 · Forecast | 58 |
| Wed 12:00 · Forecast | 58 |
| Wed 13:00 · Forecast | 58 |
| Wed 14:00 · Forecast | 57 |
| Wed 15:00 · Forecast | 57 |
| Wed 16:00 · Forecast | 57 |
| Wed 17:00 · Forecast | 56 |
| Wed 18:00 · Forecast | 55 |
| Wed 19:00 · Forecast | 51 |
| Wed 20:00 · Forecast | 45 |
| Wed 21:00 · Forecast | 43 |
| Wed 22:00 · Forecast | 42 |
| Wed 23:00 · Forecast | 43 |
Pollutants this hour
- PM2.5 9.6 µg/m³ 24-hour mean 10.5 µg/m³ · within WHO’s 24-hour guideline (15) 55
- PM10 14 µg/m³ 14
- O₃ 65 µg/m³ 29
- NO₂ 14 µg/m³ 7
- SO₂ 1 µg/m³ 0
- CO 0.12 mg/m³ 1
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
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 Francisco’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