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South San Francisco, California

City in San Mateo County, California

Air quality

The air at South San Francisco

Index 39, good, led by fine particles. Read at 9 PM from its reporting area, San Francisco (CA), 6 miles off.

39Good
  • Fine particles (PM2.5)39Good7.5 mi
  • Ozone26Good24 ppb7.5 mi
  • Nitrogen dioxide12Good13 ppb7.5 mi
  • Sulfur dioxide0Good0.4 ppb13.4 mi
  • Carbon monoxide-0.5 ppm7.5 mi

The days ahead

Highest moderate, Sat Oct 17, led by fine particles. Yesterday measured 43, good.

Smoke, the next 45 hours

Little smoke near the ground through Sat 5 PM: the index from smoke stays at 11 or under.

FriSat

Precipitation

What has fallen at South San Francisco

None in the last 3 days, to Thu 8 PM. Measured by radar and rain gauges, as water.

Last 24 hours
0.00in
Last 3 days
0.00in

Visibility

How far you can see at South San Francisco, the next 45 hours

Visibility stays 10 miles or more through Sat 5 PM.

FriSat

On the radar over South San Francisco, CaliforniaReflectivityStorm topsRain rateRain, last 24 hoursForecast temperatureForecast rain totalEvery picture

What is measuring near here

The 5 instruments nearest South San Francisco, how far away each one is, how high it stands, and what kind of measurement it makes. The nearest is 0.7 miles away.

measured now3 instruments

measured daily2 instruments

South San Francisco 6.1 WCA-SM-50

In a volunteer observer's own ground/0.7 mi away/38 ft/level with here

precip, snowfall, snow depth

Rank-

San Francisco OceansideSRSC1

At a cooperative observer's station/6.3 mi away/67 ft/29 ft above here

snowfall, snow depth, precip, high, low

Rank-

Station report

The weather at San Francisco INTL, drawn

The nearest airport reporting now, 4.1 mi from South San Francisco, California. From its report of Oct 15, 2026, 8:56 PM local time: 3 of its 6 sheets.

The sky

No cloud below 12,000 ft; visibility 10 mi or more.

Section of the sky over San Francisco INTL, height above the station to scale: no cloud detected below 12,000 feet, the reach of its ceilometer, and visibility of 10 mi or more.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT SFOFIG. A THE SKY OVER SAN FRANCISCO INTLSECTION, HEIGHT ABOVE THE STATION TO SCALE, EACH LAYER AT THE HEIGHT OF ITS BASE AS REPORTED; COVER IN EIGHTHS OF THE SKY; TOPS NOT MEASUREDFT ABOVE THE STATION05001,0001,5002,0002,5003,000ETAGESLOWTHE STATIONTHE CEILOMETER READS TO 12,000 FT, ABOVE THIS SHEETNO CLOUD DETECTED BELOW 12,000 FTVISIBILITY, MILES: 10 MI OR MORE0510TITLESan Francisco INTL, the skySTATION REPORT · ASOS SFOTYPESECTIONSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 1 of 6DATE2026-10-16IDSR-SFO-1DRAWN AS linework on paperSOURCES FB-SKY-001

The air

70.0 F with a dew point of 43.0 F, 38 per cent relative humidity. Air lifted from the station would cool to its dew point, where cloud forms, about 6,100 ft up.

Chart of the air at San Francisco INTL: temperature 70.0 degrees Fahrenheit and dew point 43.0, 38 per cent relative humidity; air lifted from the station cools along the dry rate and meets its dew point about 6,100 feet above the station; height to scale.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT SFOFIG. B THE AIR AT SAN FRANCISCO INTLTHE REPORTED TEMPERATURE AND DEW POINT, AND AIR LIFTED FROM THE STATION WITHOUT MIXING UNTIL IT SATURATES; HEIGHT ABOVE THE STATION TO SCALEFT ABOVE THE STATION01,0002,0003,0004,0005,0006,0007,0008,00030 F40 F50 F60 F70 F80 FSATURATES 6,100 FT ABOVE THE STATION, AT 37.2 FTEMPERATURE 70.0 FDEW POINT 43.0 FSPREAD 27.0 FRELATIVE HUMIDITY 38 PER CENTTHE AIR COOLS ABOUT 5.4 F EACH 1,000 FT IT RISES, AND ITS DEW POINT ABOUT 1 FSOLID: THE LIFTED AIR'S TEMPERATURE; DASHED: ITS DEW POINTTITLESan Francisco INTL, the airSTATION REPORT · ASOS SFOTYPECHARTSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 2 of 6DATE2026-10-16IDSR-SFO-2DRAWN AS linework on paperSOURCES FB-WAT-002, FB-ENG-011, FB-ENG-005

The wind

From the west northwest (300 degrees) at 8 mph: force 3, a gentle breeze on the Beaufort scale.

Plan of the wind at San Francisco INTL, north up: blowing from 300 degrees, the west northwest, at 8 miles an hour; beside it the Beaufort scale from calm to hurricane force, force 3, gentle breeze, marked.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT SFOFIG. C THE WIND AT SAN FRANCISCO INTLPLAN, NORTH UP: THE WIND AS REPORTED, AND WHERE IT SITS ON THE BEAUFORT SCALENESWTHE STATIONFROM 300°BEAUFORT FORCELEAST WIND, MPH0CALM01LIGHT AIR12LIGHT BREEZE43GENTLE BREEZE8NOW, 8 MPH4MODERATE BREEZE135FRESH BREEZE196STRONG BREEZE257NEAR GALE328GALE399STRONG GALE4710STORM5511VIOLENT STORM6412HURRICANE FORCE73TITLESan Francisco INTL, the windSTATION REPORT · ASOS SFOTYPEPLAN north upSCALENOT TO SCALEREVAS REPORTED SHEET 3 of 6DATE2026-10-16IDSR-SFO-3DRAWN AS linework on paperSOURCES FB-EVT-150, FB-ENG-008, FB-INS-002

The full report of San Francisco INTL, in 6 sheets, each beside the Field Book plates that explain it

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Snow on the ground

Elsewhere in California

33 places, each with its own forecast and its own instruments.

Near South San Francisco

The nearest places, each with its own forecast and the instruments nearest it.

Near South San Francisco

River and lake gauges