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Potomac, Maryland

Community in Montgomery County, Maryland

Air quality

The air at Potomac

Index 26, good, led by fine particles. Read at 12 AM from its reporting area, Suburban DC (MD), 11 miles off.

26Good
  • Fine particles (PM2.5)26Good19.5 mi
  • Ozone24Good24 ppb7 mi
  • Nitrogen dioxide3Good3.8 ppb16.3 mi
  • Sulfur dioxide0Good0.1 ppb16.3 mi
  • Carbon monoxide-0.1 ppm16.3 mi

The days ahead

Good each day through Wed Oct 21, led by fine particles. Yesterday measured 21, good.

Smoke, the next 45 hours

No smoke near the ground through Sun 8 PM.

SatSun

Precipitation

What has fallen at Potomac

0.23 in in the last 24 hours, and none in the 2 days before, to Fri 11 PM. Measured by radar and rain gauges, as water.

Last 24 hours
0.23in
Last 3 days
0.23in

Visibility

How far you can see at Potomac, the next 45 hours

Visibility stays 5 miles or more through Sun 8 PM, lowest 6 miles Sat 5 AM.

SatSun

On the radar over Potomac, MarylandReflectivityStorm topsRain rateRain, last 24 hoursForecast temperatureForecast rain totalEvery picture

What is measuring near here

The 7 instruments nearest Potomac, how far away each one is, how high it stands, and what kind of measurement it makes. The nearest is 1.2 miles away.

measured now5 instruments

GaithersburgGAI

At an airfield/9.4 mi away/539 ft/211 ft above here

temp, wind, gust, visibility, precip, pressure

Rank83of 742

Powder MillS2049

At a soil climate station/17.8 mi away/105 ft/223 ft below here

temp, humidity, soil temp, soil moisture

Rank726of 742

measured daily2 instruments

Potomac 0.9 NNWMD-MG-3

In a volunteer observer's own ground/1.4 mi away/318 ft/10 ft below here

precip, snowfall, snow depth

Rank-

BeltsvilleBTVM2

At a cooperative observer's station/16.0 mi away/138 ft/190 ft below here

snowfall, snow depth, precip, high, low

Rank-

Station report

The weather at Gaithersburg, drawn

The nearest airport reporting now, 9.4 mi from Potomac, Maryland. From its report of Oct 16, 2026, 11:56 PM local time: 3 of its 6 sheets.

The sky

Overcast at 8,500 ft; the ceiling is 8,500 ft; visibility 10 mi or more.

Section of the sky over Gaithersburg, height above the station to scale: overcast cloud with its base at 8,500 feet, the ceiling at 8,500 feet, and visibility of 10 mi or more.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT GAIFIG. A THE SKY OVER GAITHERSBURGSECTION, 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 STATION02,5005,0007,50010,00012,50015,000ETAGESLOWMIDDLETHE STATIONTHE CEILOMETER READS TO 12,000 FTOVC 8,500 FTOVERCAST, 8 EIGHTHS OF THE SKYCEILING 8,500 FTVISIBILITY, MILES: 10 MI OR MORE0510TITLEGaithersburg, the skySTATION REPORT · ASOS GAITYPESECTIONSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 1 of 6DATE2026-10-17IDSR-GAI-1DRAWN AS linework on paperSOURCES FB-SKY-001, FB-SKY-013, FB-SKY-014

The air

61.0 F with a dew point of 52.0 F, 72 per cent relative humidity. Air lifted from the station would cool to its dew point, where cloud forms, about 2,100 ft up; the lowest cloud reported is at 8,500 ft.

Chart of the air at Gaithersburg: temperature 61.0 degrees Fahrenheit and dew point 52.0, 72 per cent relative humidity; air lifted from the station cools along the dry rate and meets its dew point about 2,100 feet above the station, against the lowest cloud reported at 8,500 feet; height to scale.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT GAIFIG. B THE AIR AT GAITHERSBURGTHE REPORTED TEMPERATURE AND DEW POINT, AND AIR LIFTED FROM THE STATION WITHOUT MIXING UNTIL IT SATURATES; HEIGHT ABOVE THE STATION TO SCALEFT ABOVE THE STATION01,0002,0003,0004,0005,0006,0007,0008,00040 F50 F60 F70 FSATURATES 2,100 FT ABOVE THE STATION, AT 49.9 FABOVE THIS SHEET: LOWEST CLOUD REPORTED, OVC 8,500 FTTEMPERATURE 61.0 FDEW POINT 52.0 FSPREAD 9.0 FRELATIVE HUMIDITY 72 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 POINTTITLEGaithersburg, the airSTATION REPORT · ASOS GAITYPECHARTSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 2 of 6DATE2026-10-17IDSR-GAI-2DRAWN AS linework on paperSOURCES FB-WAT-002, FB-ENG-011, FB-ENG-005

The wind

From the west northwest (300 degrees) at 12 mph: force 3, a gentle breeze on the Beaufort scale. The strongest gust today was 20 mph.

Plan of the wind at Gaithersburg, north up: blowing from 300 degrees, the west northwest, at 12 miles an hour; beside it the Beaufort scale from calm to hurricane force, force 3, gentle breeze, marked.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT GAIFIG. C THE WIND AT GAITHERSBURGPLAN, NORTH UP: THE WIND AS REPORTED, AND WHERE IT SITS ON THE BEAUFORT SCALENESWTHE STATIONFROM 300°BEAUFORT FORCELEAST WIND, MPH0CALM01LIGHT AIR12LIGHT BREEZE43GENTLE BREEZE8NOW, 12 MPH4MODERATE BREEZE135FRESH BREEZE196STRONG BREEZE257NEAR GALE328GALE399STRONG GALE4710STORM5511VIOLENT STORM6412HURRICANE FORCE73TITLEGaithersburg, the windSTATION REPORT · ASOS GAITYPEPLAN north upSCALENOT TO SCALEREVAS REPORTED SHEET 3 of 6DATE2026-10-17IDSR-GAI-3DRAWN AS linework on paperSOURCES FB-EVT-150, FB-ENG-008, FB-INS-002

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

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Snow on the ground

Elsewhere in Maryland

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

Near Potomac

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

Near Potomac

River and lake gauges