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Herndon, Virginia

Town in Fairfax County, Virginia

Air quality

The air at Herndon

Index 25, good, led by fine particles. Read at 11 PM from its reporting area, Northern Virginia (VA), 6 miles off.

25Good
  • Fine particles (PM2.5)25Good18.2 mi
  • Ozone15Good10 ppb18.2 mi
  • Coarse particles (PM10)7Good-
  • Nitrogen dioxide4Good4.2 ppb20.5 mi
  • Carbon monoxide-0.3 ppm20.5 mi

The days ahead

Good each day through Sun Oct 18, led by fine particles. Yesterday measured 52, moderate.

Smoke, the next 45 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 Herndon

0.01 in in the last 24 hours, and none in the 2 days before, to Thu 11 PM. 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 Herndon, the next 45 hours

Visibility stays 7 miles or more through Sat 8 PM, lowest 8 miles Fri 5 AM.

FriSat

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

What is measuring near here

The 5 instruments nearest Herndon, how far away each one is, how high it stands, and what kind of measurement it makes. The nearest is 0.6 miles away.

measured now3 instruments

measured daily2 instruments

Herndon 0.4 ENEVA-FX-9

In a volunteer observer's own ground/0.6 mi away/387 ft/2 ft above here

precip, snowfall, snow depth

Rank-

Station report

The weather at Washington/Dulles, drawn

The nearest airport reporting now, 3.8 mi from Herndon, Virginia. From its report of Oct 16, 2026, 12:07 AM local time: 3 of its 6 sheets.

The sky

Broken at 1,300 ft, overcast at 1,900 ft; the ceiling is 1,300 ft; visibility 5 mi.

Section of the sky over Washington/Dulles, height above the station to scale: broken cloud with its base at 1,300 feet, overcast cloud with its base at 1,900 feet, the ceiling at 1,300 feet, and visibility of 5 mi.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 1,900 FTOVERCAST, 8 EIGHTHS OF THE SKYBKN 1,300 FTBROKEN, 5 TO 7 EIGHTHS OF THE SKYCEILING 1,300 FTVISIBILITY, MILES: 5 MI0510TITLEWashington/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 58.0 F, 93 per cent relative humidity. Air lifted from the station would cool to its dew point, where cloud forms, about 500 ft up; the lowest cloud reported is at 1,300 ft.

Chart of the air at Washington/Dulles: temperature 60.0 degrees Fahrenheit and dew point 58.0, 93 per cent relative humidity; air lifted from the station cools along the dry rate and meets its dew point about 500 feet above the station, against the lowest cloud reported at 1,300 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 500 FT ABOVE THE STATION, AT 57.5 FLOWEST CLOUD REPORTED, BKN 1,300 FTTEMPERATURE AND DEW POINT 60.0 F, 58.0 FRELATIVE HUMIDITY 93 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 (170 degrees) at 5 mph: force 2, a light breeze on the Beaufort scale.

Plan of the wind at Washington/Dulles, north up: blowing from 170 degrees, the south, at 5 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 170°BEAUFORT FORCELEAST WIND, MPH0CALM01LIGHT AIR12LIGHT BREEZE4NOW, 5 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

0in

Snow on the ground

Measured at Sterling WFO (KCIV2), 5.2 miles from here, read 15 Oct, 20:00. measured daily

Elsewhere in Virginia

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

Near Herndon

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

Near Herndon

River and lake gauges