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Union Mill, Virginia

Community in Fairfax County, Virginia

Air quality

The air at Union Mill

Index 26, good, led by fine particles. Read at 3 AM from its reporting area, Northern Virginia (VA), 7 miles off.

26Good
  • Fine particles (PM2.5)26Good-
  • Ozone14Good-
  • Coarse particles (PM10)8Good-

The days ahead

Good each day through Sun Oct 18, led by fine particles. Yesterday measured 28, good.

Smoke, the next 41 hours

Little smoke near the ground through Sat 8 PM: the index from smoke stays at 6 or under.

FriSat

Precipitation

What has fallen at Union Mill

0.01 in in the last 24 hours, and none in the 2 days before, to Fri 2 AM. Measured by radar and rain gauges, as water.

Last 24 hours
0.01in
Last 3 days
0.01in

Visibility

How far you can see at Union Mill, the next 41 hours

Visibility stays 7 miles or more through Sat 8 PM, lowest 8 miles Fri 8 AM.

FriSat

On the radar over Union Mill, VirginiaReflectivityStorm topsRain rateRain, last 24 hoursForecast temperatureForecast rain totalEvery picture

What is measuring near here

The 5 instruments nearest Union Mill, how far away each one is, how high it stands, and what kind of measurement it makes. The nearest is 1.7 miles away.

measured now3 instruments

measured daily2 instruments

Centreville 1.3 SEVA-FX-20

In a volunteer observer's own ground/2.3 mi away/400 ft/4 ft below here

precip, snowfall, snow depth

Rank-

ManassasMNNV2

At a cooperative observer's station/8.0 mi away/256 ft/148 ft below here

snowfall, snow depth, precip, high, low

Rank-

Station report

The weather at Washington/Dulles, drawn

The nearest airport reporting now, 8.7 mi from Union Mill, Virginia. From its report of Oct 16, 2026, 2:52 AM local time: 3 of its 6 sheets.

The sky

Overcast at 600 ft; the ceiling is 600 ft; visibility 10 mi or more.

Section of the sky over Washington/Dulles, height above the station to scale: overcast cloud with its base at 600 feet, the ceiling at 600 feet, and visibility of 10 mi or more.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT IADFIG. A THE SKY OVER WASHINGTON/DULLESSECTION, 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 SHEETOVC 600 FTOVERCAST, 8 EIGHTHS OF THE SKYCEILING 600 FTVISIBILITY, MILES: 10 MI OR MORE0510TITLEWashington/Dulles, the skySTATION REPORT · ASOS IADTYPESECTIONSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 1 of 6DATE2026-10-16IDSR-IAD-1DRAWN AS linework on paperSOURCES FB-SKY-001, FB-SKY-017, FB-SKY-016, FB-SKY-018

The air

60.0 F with a dew point of 59.0 F, 96 per cent relative humidity. Air lifted from the station would cool to its dew point, where cloud forms, about 200 ft up; the lowest cloud reported is at 600 ft.

Chart of the air at Washington/Dulles: temperature 60.0 degrees Fahrenheit and dew point 59.0, 96 per cent relative humidity; air lifted from the station cools along the dry rate and meets its dew point about 200 feet above the station, against the lowest cloud reported at 600 feet; height to scale.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT IADFIG. B THE AIR AT WASHINGTON/DULLESTHE REPORTED TEMPERATURE AND DEW POINT, AND AIR LIFTED FROM THE STATION WITHOUT MIXING UNTIL IT SATURATES; HEIGHT ABOVE THE STATION TO SCALEFT ABOVE THE STATION01,0002,0003,00050 F60 F70 FSATURATES 200 FT ABOVE THE STATION, AT 58.7 FLOWEST CLOUD REPORTED, OVC 600 FTTEMPERATURE AND DEW POINT 60.0 F, 59.0 FRELATIVE HUMIDITY 96 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 POINTTITLEWashington/Dulles, the airSTATION REPORT · ASOS IADTYPECHARTSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 2 of 6DATE2026-10-16IDSR-IAD-2DRAWN AS linework on paperSOURCES FB-WAT-020, FB-WAT-002, FB-ENG-011, FB-ENG-005

The wind

From the south (180 degrees) at 6 mph: force 2, a light breeze on the Beaufort scale.

Plan of the wind at Washington/Dulles, north up: blowing from 180 degrees, the south, at 6 miles an hour; beside it the Beaufort scale from calm to hurricane force, force 2, light breeze, marked.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT IADFIG. C THE WIND AT WASHINGTON/DULLESPLAN, NORTH UP: THE WIND AS REPORTED, AND WHERE IT SITS ON THE BEAUFORT SCALENESWTHE STATIONFROM 180°BEAUFORT FORCELEAST WIND, MPH0CALM01LIGHT AIR12LIGHT BREEZE4NOW, 6 MPH3GENTLE BREEZE84MODERATE BREEZE135FRESH BREEZE196STRONG BREEZE257NEAR GALE328GALE399STRONG GALE4710STORM5511VIOLENT STORM6412HURRICANE FORCE73TITLEWashington/Dulles, the windSTATION REPORT · ASOS IADTYPEPLAN north upSCALENOT TO SCALEREVAS REPORTED SHEET 3 of 6DATE2026-10-16IDSR-IAD-3DRAWN AS linework on paperSOURCES FB-EVT-150, FB-ENG-008, FB-INS-002

The full report of Washington/Dulles, in 6 sheets, each beside the Field Book plates that explain it

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Snow on the ground

Elsewhere in Virginia

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

Near Union Mill

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

Near Union Mill

River and lake gauges