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Alta, California

Community in Placer County, California

Air quality

The air at Alta

Index 27, good, led by ozone. Read at 1 AM from its reporting area, Colfax (CA), 11 miles off.

27Good
  • Fine particles (PM2.5)24Good11.2 mi
  • Ozone27Good27 ppb11.2 mi

The days ahead

Highest 58, moderate, today, led by ozone. Yesterday measured 29, good.

Smoke, the next 40 hours

No smoke near the ground through Sat 5 PM.

FriSat

Precipitation

What has fallen at Alta

None in the last 3 days, to Fri 1 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 Alta, the next 40 hours

Visibility stays 10 miles or more through Sat 5 PM.

FriSat

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

What is measuring near here

The 6 instruments nearest Alta, how far away each one is, how high it stands, and what kind of measurement it makes. The nearest is 2.4 miles away.

measured now4 instruments

measured daily2 instruments

Dutch Flat 0.7 SCA-PC-59

In a volunteer observer's own ground/2.4 mi away/3,182 ft/574 ft below here

precip, snowfall, snow depth

Rank-

Gold Run 2SWGLRC1

At a cooperative observer's station/4.6 mi away/3,143 ft/613 ft below here

snowfall, snow depth, precip, high, low

Rank-

Station report

The weather at Blue Canyon - Nyack, drawn

The nearest airport reporting now, 6.4 mi from Alta, California. From its report of Oct 16, 2026, 1:52 AM 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 Blue Canyon - Nyack, 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 BLUFIG. A THE SKY OVER BLUE CANYON - NYACKSECTION, 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 MORE0510TITLEBlue Canyon - Nyack, the skySTATION REPORT · ASOS BLUTYPESECTIONSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 1 of 6DATE2026-10-16IDSR-BLU-1DRAWN AS linework on paperSOURCES FB-SKY-001

The air

61.0 F with a dew point of 19.0 F, 19 per cent relative humidity. Air lifted from the station would cool to its dew point, where cloud forms, about 9,400 ft up.

Chart of the air at Blue Canyon - Nyack: temperature 61.0 degrees Fahrenheit and dew point 19.0, 19 per cent relative humidity; air lifted from the station cools along the dry rate and meets its dew point about 9,400 feet above the station; height to scale.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT BLUFIG. B THE AIR AT BLUE CANYON - NYACKTHE REPORTED TEMPERATURE AND DEW POINT, AND AIR LIFTED FROM THE STATION WITHOUT MIXING UNTIL IT SATURATES; HEIGHT ABOVE THE STATION TO SCALEFT ABOVE THE STATION02,0004,0006,0008,00010,00012,0000 F20 F40 F60 FSATURATES 9,400 FT ABOVE THE STATION, AT 10.9 FTEMPERATURE 61.0 FDEW POINT 19.0 FSPREAD 42.0 FRELATIVE HUMIDITY 19 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 POINTTITLEBlue Canyon - Nyack, the airSTATION REPORT · ASOS BLUTYPECHARTSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 2 of 6DATE2026-10-16IDSR-BLU-2DRAWN AS linework on paperSOURCES FB-WAT-002, FB-ENG-011, FB-ENG-005

The wind

From the northeast (50 degrees) at 10 mph, gusting 30 mph: force 3, a gentle breeze on the Beaufort scale. The strongest gust today was 32 mph.

Plan of the wind at Blue Canyon - Nyack, north up: blowing from 50 degrees, the northeast, at 10 miles an hour, gusting 30; beside it the Beaufort scale from calm to hurricane force, force 3, gentle breeze, marked.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT BLUFIG. C THE WIND AT BLUE CANYON - NYACKPLAN, NORTH UP: THE WIND AS REPORTED, AND WHERE IT SITS ON THE BEAUFORT SCALENESWTHE STATIONFROM 50°BEAUFORT FORCELEAST WIND, MPH0CALM01LIGHT AIR12LIGHT BREEZE43GENTLE BREEZE8NOW, 10 MPH4MODERATE BREEZE135FRESH BREEZE196STRONG BREEZE25GUST, 30 MPH7NEAR GALE328GALE399STRONG GALE4710STORM5511VIOLENT STORM6412HURRICANE FORCE73TITLEBlue Canyon - Nyack, the windSTATION REPORT · ASOS BLUTYPEPLAN north upSCALENOT TO SCALEREVAS REPORTED SHEET 3 of 6DATE2026-10-16IDSR-BLU-3DRAWN AS linework on paperSOURCES FB-EVT-150, FB-ENG-008, FB-INS-002

The full report of Blue Canyon - Nyack, 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 Alta

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

Near Alta

River and lake gauges