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Longmont, Colorado

City in Boulder County, Colorado

Air quality

The air at Longmont

Index 79, moderate, led by fine particles. Read at 11 PM from its reporting area, Denver-Boulder (CO), 19 miles off.

79Moderate
  • Fine particles (PM2.5)79Moderate0.6 mi
  • Ozone28Good13 ppb9 mi
  • Coarse particles (PM10)19Good13.7 mi
  • Nitrogen dioxide15Good16.1 ppb24.4 mi
  • Sulfur dioxide0Good0 ppb24.4 mi
  • Carbon monoxide-0.1 ppm24.7 mi

The days ahead

Good each day through Today, led by fine particles. Yesterday measured 43, good.

Smoke, the next 43 hours

No smoke near the ground through Sat 6 PM.

FriSat

Precipitation

What has fallen at Longmont

0.08 in in the last 24 hours, 0.63 in over the last 3 days, to Thu 11 PM. Measured by radar and rain gauges, as water.

Last 24 hours
0.08in
Last 3 days
0.63in

Visibility

How far you can see at Longmont, the next 43 hours

Visibility stays 10 miles or more through Sat 6 PM.

FriSat

On the radar over Longmont, ColoradoReflectivityStorm topsRain rateRain, last 24 hoursForecast temperatureForecast rain totalEvery picture

What is measuring near here

The 7 instruments nearest Longmont, how far away each one is, how high it stands, and what kind of measurement it makes. The nearest is 0.3 miles away.

measured now5 instruments

measured daily2 instruments

Station report

The weather at Longmont/Vbrand, drawn

The nearest airport reporting now, 3.1 mi from Longmont, Colorado. From its report of Oct 15, 2026, 11:55 PM 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 Longmont/Vbrand, 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 LMOFIG. A THE SKY OVER LONGMONT/VBRANDSECTION, 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 MORE0510TITLELongmont/Vbrand, the skySTATION REPORT · ASOS LMOTYPESECTIONSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 1 of 6DATE2026-10-16IDSR-LMO-1DRAWN AS linework on paperSOURCES FB-SKY-001

The air

36.7 F with a dew point of 33.8 F, 89 per cent relative humidity. Air lifted from the station would cool to its dew point, where cloud forms, about 700 ft up.

Chart of the air at Longmont/Vbrand: temperature 36.7 degrees Fahrenheit and dew point 33.8, 89 per cent relative humidity; air lifted from the station cools along the dry rate and meets its dew point about 700 feet above the station; height to scale.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT LMOFIG. B THE AIR AT LONGMONT/VBRANDTHE REPORTED TEMPERATURE AND DEW POINT, AND AIR LIFTED FROM THE STATION WITHOUT MIXING UNTIL IT SATURATES; HEIGHT ABOVE THE STATION TO SCALEFT ABOVE THE STATION01,0002,0003,00020 F30 F40 F50 FSATURATES 700 FT ABOVE THE STATION, AT 33.1 FTEMPERATURE AND DEW POINT 36.7 F, 33.8 FRELATIVE HUMIDITY 89 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 POINTTITLELongmont/Vbrand, the airSTATION REPORT · ASOS LMOTYPECHARTSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 2 of 6DATE2026-10-16IDSR-LMO-2DRAWN AS linework on paperSOURCES FB-WAT-020, FB-WAT-002, FB-ENG-011, FB-ENG-005

The wind

From the west southwest (250 degrees) at 5 mph: force 2, a light breeze on the Beaufort scale. The strongest gust today was 32 mph.

Plan of the wind at Longmont/Vbrand, north up: blowing from 250 degrees, the west southwest, 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 LMOFIG. C THE WIND AT LONGMONT/VBRANDPLAN, NORTH UP: THE WIND AS REPORTED, AND WHERE IT SITS ON THE BEAUFORT SCALENESWTHE STATIONFROM 250°BEAUFORT FORCELEAST WIND, MPH0CALM01LIGHT AIR12LIGHT BREEZE4NOW, 5 MPH3GENTLE BREEZE84MODERATE BREEZE135FRESH BREEZE196STRONG BREEZE257NEAR GALE328GALE399STRONG GALE4710STORM5511VIOLENT STORM6412HURRICANE FORCE73TITLELongmont/Vbrand, the windSTATION REPORT · ASOS LMOTYPEPLAN north upSCALENOT TO SCALEREVAS REPORTED SHEET 3 of 6DATE2026-10-16IDSR-LMO-3DRAWN AS linework on paperSOURCES FB-EVT-150, FB-ENG-008, FB-INS-002

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

0in

Snow on the ground

Measured at Longmont Profiler (LONC2), 1.6 miles from here, read 15 Oct, 07:15. measured daily

Elsewhere in Colorado

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

Near Longmont

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

Near Longmont

River and lake gauges