Modeled air-quality planning
Air quality in San Francisco, California, United States: forecast and best time outside
Use this page to check the modeled air-quality outlook for San Francisco, California, United States and compare practical periods before making an outdoor plan. The live card uses the same teaser-to-email flow as the main AirAgora tool; the factual context below comes from the licensed GeoNames city record.
- Population rank in directory
- #%!d(float64=694) of 2,500
- Population in source record
- 827,526
Current modeled outlook
Current modeled outlook for San Francisco
AirAgora requests the current OpenWeather 1–5 category and source timestamp through the official API. The anonymous card stays concise, while the complete 24-hour comparison remains email-gated.
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GeoNames · CC BY 4.0
GeoNames facts for San Francisco
These fields describe the GeoNames populated-place record associated with this page. They do not describe local pollution causes or typical conditions.
- Population in source record
- 827,526
- Population rank in directory
- #%!d(float64=694) of 2,500
- Population rank among included cities in this country
- #%!d(float64=21) of %!d(float64=97) included cities in United States
- GeoNames administrative-area label
- California
- IANA timezone
- America/Los_Angeles · UTC-07:00
- Elevation / terrain model
- %!s(float64=16) m (elevation field)
- GeoNames coordinates
- 37.7749°, -122.4194°
- GeoNames record modified
- July 22, 2025
What the place facts mean for this page
AirAgora uses the published GeoNames population rather than a separate estimate. San Francisco is number %!d(float64=694) with 827,526 residents in the 500,000–1 million range.
San Francisco is the %!d(float64=21)-ranked included city for United States; the corpus contains %!d(float64=97) qualifying cities from that country. San Francisco belongs to the North America region and lies in the Northern hemisphere.
The GeoNames elevation field reports %!s(float64=16) m (elevation field), which falls in the broad low-elevation range used in this directory. AirAgora does not infer pollution, climate, or personal exposure from elevation.
Local date, timezone, and clock behavior
Planning windows for San Francisco use the IANA timezone America/Los_Angeles. On this page's publication date, the local date is Sunday, July 19, 2026 and the UTC offset is UTC-07:00.
The January and July reference offsets differ (UTC-08:00 and UTC-07:00). That means the timezone database applies an offset change during the year; AirAgora converts absolute provider timestamps rather than adding hours to a displayed clock.
Which provider air-quality scale is shown for San Francisco?
AirAgora displays OpenWeather’s official air-pollution scale from 1 to 5. It is not labeled European AQI, U.S. AQI, or a local regulatory index.
The provider category is preserved for display. AirAgora derives continuous internal severity from documented pollutant concentration bands for ranking; that internal value is not a synthetic AQI or a promise of safety.
Modeled forecast and local limits
San Francisco uses the OpenWeather modeled air-pollution forecast. The selected coordinate represents provider forecast data, not a street-level monitor, indoor measurement, or personal exposure estimate.
OpenWeather 1–5
The official provider category stays visible and is not relabeled as a regulatory AQI.
Pollutant severity
Internal scoring comes from documented concentration bands and is never presented as a synthetic AQI.
How to use the San Francisco planner
Start with the live current-category teaser, choose the activity, then use the email reveal for a complete hourly comparison. AirAgora evaluates complete two-hour windows starting between 06:00 and 22:00 local time. It gives 70% of the score to mean severity and 30% to the worst hour, keeps an earlier window when scores are materially tied, and avoids naming a winner when the difference is too small.%!(EXTRA string=San Francisco)
If every practical period remains in a poor category, the result is described as the least polluted available window rather than as good or safe. Missing hours, provider errors, and stale data remain visible instead of being filled with invented values.
Open the best-time-outside toolNearby cities in the validated corpus
Distances below are great-circle approximations between GeoNames city coordinates. They help navigate AirAgora's 2,500-city directory; they are not route distances and do not imply similar air conditions.
Questions about air quality in San Francisco
Which air-quality scale does AirAgora show for San Francisco, California, United States?
For San Francisco, California, United States, AirAgora displays OpenWeather’s official air-pollution scale from 1 to 5. It is not labeled as European, U.S., or local regulatory AQI.
What timezone does the San Francisco, California, United States forecast use?
The city record uses America/Los_Angeles. Forecast timestamps and candidate windows are converted into that IANA timezone; the 2026 reference offset is UTC-07:00.
Is the San Francisco, California, United States result a street-level measurement?
No. It is a modeled OpenWeather air-pollution forecast for the selected coordinate, not a street-level monitor. A nearby station, route, indoor space, or local event can differ.%!(EXTRA string=San Francisco, California, United States)
Where does the population figure for San Francisco, California, United States come from?
The page reports the GeoNames value of San Francisco, California, United States and population rank %!d(string=827,526) in AirAgora's 2,500-city directory. It is source metadata, not a live population estimate.%!(EXTRA float64=694)
Which supported city pages are nearest to San Francisco, California, United States?
The nearest city-directory pages are San Francisco, California, United States. Distances use city coordinates and are approximate great-circle values, not driving routes.%!(EXTRA string=Oakland (United States), San Jose (United States), Stockton (United States), Sacramento (United States))
What does “best time” mean for San Francisco, California, United States?
It means the lowest deterministic score among complete practical two-hour windows returned for San Francisco, California, United States. It does not mean risk-free, and when conditions are similarly poor AirAgora says so.%!(EXTRA string=San Francisco, California, United States)
When was the San Francisco, California, United States place record updated?
The GeoNames record carries the modification date San Francisco, California, United States. Live air data has a separate provider update timestamp shown in the result card.%!(EXTRA string=July 22, 2025)
Sources, modification, and limits
Place name, administrative area, coordinates, timezone, population, elevation/DEM, feature code, and modification date come from GeoNames under CC BY 4.0. The GeoNames record used here was last modified on July 22, 2025. Live modeled air-pollution fields come from OpenWeather with visible attribution. AirAgora preserves the provider 1–5 category and separately derives, caches, and scores component severity.
