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Hillsborough, California

Town in San Mateo County, California

Air quality

The air at Hillsborough

Index 34, good, led by fine particles. Read at 8 PM from its reporting area, Redwood City (CA), 9 miles off.

34Good
  • Fine particles (PM2.5)34Good-
  • Ozone28Good-

The days ahead

Good each day through Tue Oct 20, led by ozone. Yesterday measured 40, good.

Smoke, the next 46 hours

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

ThuFriSat

Precipitation

What has fallen at Hillsborough

None in the last 3 days, to Thu 7 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 Hillsborough, the next 46 hours

Visibility stays 10 miles or more through Sat 5 PM.

ThuFriSat

On the radar over Hillsborough, CaliforniaReflectivityStorm topsRain rateRain, last 24 hoursForecast temperatureForecast rain totalEvery picture

What is measuring near here

The 5 instruments nearest Hillsborough, how far away each one is, how high it stands, and what kind of measurement it makes. The nearest is 1.4 miles away.

measured now3 instruments

measured daily2 instruments

Half Moon BayHMBC1

At a cooperative observer's station/7.6 mi away/23 ft/307 ft below here

snowfall, snow depth, precip, high, low

Rank122of 4,465

Station report

The weather at San Francisco INTL, drawn

The nearest airport reporting now, 4.3 mi from Hillsborough, California. From its report of Oct 15, 2026, 7:56 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

73.0 F with a dew point of 41.0 F, 31 per cent relative humidity. Air lifted from the station would cool to its dew point, where cloud forms, about 7,300 ft up.

Chart of the air at San Francisco INTL: temperature 73.0 degrees Fahrenheit and dew point 41.0, 31 per cent relative humidity; air lifted from the station cools along the dry rate and meets its dew point about 7,300 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 STATION02,0004,0006,0008,00010,00020 F30 F40 F50 F60 F70 F80 FSATURATES 7,300 FT ABOVE THE STATION, AT 34.2 FTEMPERATURE 73.0 FDEW POINT 41.0 FSPREAD 32.0 FRELATIVE HUMIDITY 31 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 (280 degrees) at 15 mph: force 4, a moderate breeze on the Beaufort scale.

Plan of the wind at San Francisco INTL, north up: blowing from 280 degrees, the west, at 15 miles an hour; beside it the Beaufort scale from calm to hurricane force, force 4, moderate 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 280°BEAUFORT FORCELEAST WIND, MPH0CALM01LIGHT AIR12LIGHT BREEZE43GENTLE BREEZE84MODERATE BREEZE13NOW, 15 MPH5FRESH 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 Hillsborough

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

Near Hillsborough

River and lake gauges