Is the air in San Francisco safe today?

Yes. Right now the US AQI in San Francisco is 41, which counts as good. Great air. A perfect time to be outside. It is expected to reach 63 (moderate) around Fri 3:00 PM.

When is the best time to be outside in San Francisco?

Fri 10:00 AM–1:00 PM. That is the cleanest stretch in the next 24 hours, with the US AQI averaging about 40. The worst hour is around Fri 3:00 PM, at 63.

What is the main pollutant in San Francisco?

Ozone (O3). It drives the index right now, at 87 µg/m³. Formed by sunlight acting on traffic and plant emissions. Highest on hot, still afternoons, often downwind of cities.

How does San Francisco's air compare with the WHO guideline?

Within the guideline. Over the next 24 hours PM2.5 averages about 12 µg/m³, against the World Health Organization's 24-hour guideline of 15 µg/m³. The other pollutants stay within their guideline levels.

How many cigarettes is a day of San Francisco's air?

About 0.6 cigarettes. Over the next 24 hours PM2.5 averages about 12 µg/m³. By Berkeley Earth's rule of thumb, 22 µg/m³ breathed for a day is roughly one cigarette.

Will air quality in San Francisco improve this week?

Tuesday looks cleanest. Its AQI peaks at 41, against 67 on Saturday, the worst day in the forecast.

San Francisco air quality

California, United States · Live AQI and hourly forecast for the next 5 days · valid Fri 9:00 AM local time

Good

US AQI, mostly O₃

Model estimate. Nearby measurements are shown separately.

Great air. A perfect time to be outside.

Next 24 hours: 40–63US AQI, highest around Fri 3:00 PM
Best time outside: Fri 10:00 AM–1:00 PMUS AQI about 40
PM_2.5 vs WHO guideline: 0.8×12 µg/m³ over 24 h, guideline 15
Cigarette equivalent: ≈ 0.6 a dayBerkeley Earth rule of thumb

Loading the live globe…

The live globe, centred on San Francisco. Switch pollutants, drag through the next 5 days or press play. Full map →

Pollutants in San Francisco right now

Pollutant	Now	Level	Next 24 h vs WHO
Fine particles PM_2.5	6.8 µg/m³	Good	0.8×
Coarse particles PM₁₀	11 µg/m³	Good	0.4×
Nitrogen dioxide NO₂	4.2 µg/m³	Good	0.3×
Ozone O₃	87 µg/m³	Good	0.9×
Sulphur dioxide SO₂	0.3 µg/m³	Good	0.0×
Carbon monoxide CO	132 µg/m³	Good	0.0×
Aerosol optical depth	0.11	Whole atmosphere · dimensionless
Desert dust	0 µg/m³	Modelled surface dust
UV index	0	Low

“Next 24 h vs WHO” compares the forecast with the World Health Organization’s 2021 guideline levels: 24-hour means of 15 µg/m³ for PM_2.5, 45 for PM₁₀, 25 for NO₂, 40 for SO₂ and 4 mg/m³ for CO, and 100 µg/m³ over 8 hours for ozone. Above 1× is above the guideline. Levels follow the US AQI, which is far less strict than the WHO, so air rated Good can still be above a guideline.

Next 48 hours

Hourly US AQI. Highest 67 around Sat 8:00 PM, lowest 40 around Fri 10:00 AM.

Good 0–50Moderate 51–100Sensitive 101–150Unhealthy 151–200Very unhealthy 201–300Hazardous 301+

5-day air quality forecast for San Francisco

Daily range of the hourly US AQI, from lowest to highest, on a scale of 0 to 150.

Day	US AQI	At worst	Worst hour	PM_2.5 avg	UV max
Fri, Nov 13	31–63	Moderate	3:00 PM	9.2	1 Low
Sat, Nov 14	59–67	Moderate	8:00 PM	15	3 Moderate
Sun, Nov 15	39–64	Moderate	12:00 AM	12	1 Low
Mon, Nov 16	32–59	Moderate	12:00 AM	8.3	3 Moderate
Tue, Nov 17	31–41	Good	8:00 AM	5.6	3 Moderate

Common questions about the air in San Francisco

Is the air in San Francisco safe today?
Yes. Right now the US AQI in San Francisco is 41, which counts as good. Great air. A perfect time to be outside. It is expected to reach 63 (moderate) around Fri 3:00 PM.
When is the best time to be outside in San Francisco?
Fri 10:00 AM–1:00 PM. That is the cleanest stretch in the next 24 hours, with the US AQI averaging about 40. The worst hour is around Fri 3:00 PM, at 63.
What is the main pollutant in San Francisco?
Ozone (O₃). It drives the index right now, at 87 µg/m³. Formed by sunlight acting on traffic and plant emissions. Highest on hot, still afternoons, often downwind of cities.
How does San Francisco's air compare with the WHO guideline?
Within the guideline. Over the next 24 hours PM_2.5 averages about 12 µg/m³, against the World Health Organization's 24-hour guideline of 15 µg/m³. The other pollutants stay within their guideline levels.
How many cigarettes is a day of San Francisco's air?
About 0.6 cigarettes. Over the next 24 hours PM_2.5 averages about 12 µg/m³. By Berkeley Earth's rule of thumb, 22 µg/m³ breathed for a day is roughly one cigarette.
Will air quality in San Francisco improve this week?
Tuesday looks cleanest. Its AQI peaks at 41, against 67 on Saturday, the worst day in the forecast.

Measured near San Francisco

Station and measurements	Distance	US AQI	Level
Unnamed sensor OpenAQ, low-cost sensor PM_2.5: 0.0 µg/m³ · Fri 9:00 AM	0.9 km	0	Good
Unnamed sensor OpenAQ, low-cost sensor PM_2.5: 0.3 µg/m³ · Fri 9:00 AM	1.0 km	2	Good
Unnamed sensor OpenAQ, low-cost sensor PM_2.5: 0.0 µg/m³ · Fri 9:00 AM	2.0 km	0	Good

Air quality near San Francisco

US AQI right now. Cleanest nearby: San Diego (26); worst: Portland (71). The tick on each bar is San Francisco, at 41.

Sacramento 121 km NE 29 Good
Fresno 260 km SE 33 Good
Los Angeles 559 km SE 51 Moderate
Las Vegas 671 km E 52 Moderate
San Diego 738 km SE 26 Good
Portland 861 km N 71 Moderate

All 162 cities →

About this forecast

Forecast from CAMS global via Open-Meteo: the Copernicus Atmosphere Monitoring Service (CAMS) model at about 40 km resolution (about 10 km inside Europe). Global runs update every 12 hours and European runs every 24 hours. Models smooth out street-level peaks, so busy roads and industrial sites can be worse than shown. Nearby station measurements are independent observations, not adjustments to the forecast. The point forecast uses Open-Meteo’s CAMS products, including a separate carbon monoxide product; it can differ from the globe’s global grid. The AQI rates each hour on the US EPA scale, the same way the map colors it; official daily figures average over 24 hours (8 for ozone), so they can read lower after a short peak. Readings for 37.77°N, 122.42°W, valid 2026-11-13 17:00 UTC.