Storm Station
Sign in

Foster City, California

City in San Mateo County, California

Air quality

The air at Foster City

Index 36, good, led by fine particles. Read at 11 AM from its reporting area, Redwood City (CA), 6 miles off.

36Good
  • Fine particles (PM2.5)36Good5.9 mi
  • Ozone19Good34 ppb5.9 mi
  • Nitrogen dioxide5Good5.3 ppb5.9 mi
  • Sulfur dioxide0Good0.8 ppb18.3 mi
  • Carbon monoxide-0.2 ppm5.9 mi

The days ahead

Good each day through Wed Oct 21, led by ozone. Yesterday measured 46, good.

Smoke, the next 43 hours

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

FriSatSun

Precipitation

What has fallen at Foster City

None in the last 3 days, to Fri 10 AM. 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 Foster City, the next 43 hours

Visibility stays 10 miles or more through Sun 5 AM.

FriSatSun

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

What is measuring near here

The 5 instruments nearest Foster City, how far away each one is, how high it stands, and what kind of measurement it makes. The nearest is 0.5 miles away.

measured now3 instruments

measured daily2 instruments

Redwood CityRWCC1

At a cooperative observer's station/5.5 mi away/16 ft/9 ft above here

snowfall, snow depth, precip, high, low

Rank291of 4,465

Station report

The weather at Citizen station GW4019, drawn

The nearest instrument reporting now, 11.5 mi from Foster City, California. From its report of undefined: 3 of its 4 sheets.

The wind

From the south southeast (157 degrees) at 2 mph, gusting 9 mph: force 1, a light air on the Beaufort scale.

Plan of the wind at Citizen station GW4019, north up: blowing from 157 degrees, the south southeast, at 2 miles an hour, gusting 9; beside it the Beaufort scale from calm to hurricane force, force 1, light air, marked.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT GW4019FIG. C THE WIND AT CITIZEN STATION GW4019PLAN, NORTH UP: THE WIND AS REPORTED, AND WHERE IT SITS ON THE BEAUFORT SCALENESWTHE STATIONFROM 157°BEAUFORT FORCELEAST WIND, MPH0CALM01LIGHT AIR1NOW, 2 MPH2LIGHT BREEZE43GENTLE BREEZE8GUST, 9 MPH4MODERATE BREEZE135FRESH BREEZE196STRONG BREEZE257NEAR GALE328GALE399STRONG GALE4710STORM5511VIOLENT STORM6412HURRICANE FORCE73TITLECitizen station GW4019, the windSTATION REPORT · CWOP GW4019TYPEPLAN north upSCALENOT TO SCALEREVAS REPORTED SHEET 1 of 4DATE2026-10-16IDSR-GW4019-1DRAWN AS linework on paperSOURCES FB-EVT-150, FB-ENG-008

The column

At 67 ft above sea level, 0 per cent of the atmosphere's air lies below the station. The standard atmosphere puts the pressure there at 29.85 inHg and the temperature at 58.8 F; the station's altimeter setting of 30.08 inHg means its barometer reads 30.01 inHg; it reports 76.0 F, 17.2 F warmer than standard.

Section from sea level of where Citizen station GW4019 stands in the atmosphere, height to scale: the station 67 feet above sea level with 0 per cent of the air below it; the standard atmosphere's pressure there, 29.85 inches of mercury, and temperature, 58.8 degrees Fahrenheit; the altimeter setting of 30.08 and the station pressure it means, 30.01.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT GW4019FIG. D WHERE CITIZEN STATION GW4019 STANDS IN THE ATMOSPHERESECTION FROM SEA LEVEL, HEIGHT TO SCALE, THE STATION IN THE STANDARD ATMOSPHEREFT ABOVE SEA LEVEL05,00010,00015,000SEA LEVEL, 29.92 inHg IN THE STANDARD ATMOSPHERECITIZEN STATION GW40190 PER CENT OF THE AIR BELOW IT67 FT10 PER CENT OF THE AIR BELOW, 2,890 FT20 PER CENT OF THE AIR BELOW, 6,050 FT30 PER CENT OF THE AIR BELOW, 9,540 FT40 PER CENT OF THE AIR BELOW, 13,470 FTSTANDARD PRESSURE HERE29.85 inHgSTANDARD TEMPERATURE HERE58.8 FALTIMETER SETTING, REPORTED30.08 inHgITS BAROMETER READS30.01 inHgTEMPERATURE, REPORTED76.0 FTITLECitizen station GW4019, the columnSTATION REPORT · CWOP GW4019TYPESECTIONSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 2 of 4DATE2026-10-16IDSR-GW4019-2DRAWN AS linework on paperSOURCES FB-ENG-001, FB-ENG-003

The sun

On Oct 16 the noon sun stands 43 degrees above the horizon at 37.46 N, and the day is 11 h 03 min long. Level ground there takes 69 per cent of the noon sunlight a surface facing the sun would.

Elevation of the noon sun at Citizen station GW4019, angles true: on Oct 16 it stands 43 degrees above the horizon, against 76 at the June solstice, 53 at the equinoxes and 29 at the December solstice; the day is 11 h 03 min long.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT GW4019FIG. E THE SUN AT CITIZEN STATION GW4019ELEVATION LOOKING WEST, SOUTH TO THE LEFT: THE NOON SUN ON THE DAY OF THE REPORT, AND AT THE SOLSTICES AND EQUINOXES; ANGLES TRUETHE STATIONJUNE SOLSTICE 76°EQUINOXES 53°DECEMBER SOLSTICE 29°OCT 16, 43°SOUTHANGLES TRUE; THE RAYS ARE OF ONE LENGTH AND DRAW DIRECTION ONLYDAY LENGTH 11 H 03 MINLEVEL GROUND TAKES 69 PER CENT OF THE NOON SUN A FACING SURFACE WOULDLATITUDE 37.46 N; THE SUN'S DECLINATION -9.1°TITLECitizen station GW4019, the sunSTATION REPORT · CWOP GW4019TYPEELEVATIONSCALEANGLES TRUEREVAS REPORTED SHEET 3 of 4DATE2026-10-16IDSR-GW4019-3DRAWN AS linework on paperSOURCES FB-ENG-007

The full report of Citizen station GW4019, in 4 sheets, each beside the Field Book plates that explain it

-

Snow on the ground

Elsewhere in California

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

Near Foster City

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

Near Foster City

River and lake gauges