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Waterloo, Illinois

City in Monroe County, Illinois

Air quality

The air at Waterloo

Index 24, good, led by fine particles. Read at 1 PM from its reporting area, St. Louis (Metro-east) (IL), 19 miles off.

24Good
  • Fine particles (PM2.5)24Good18.8 mi
  • Ozone19Good20 ppb15.4 mi
  • Coarse particles (PM10)12Good15.4 mi
  • Nitrogen dioxide1Good1.5 ppb15.4 mi
  • Sulfur dioxide0Good0.5 ppb13.5 mi
  • Carbon monoxide-0.1 ppm21.3 mi

The days ahead

Good each day through Mon Oct 19, led by fine particles. Yesterday measured 39, good.

Smoke, the next 43 hours

No smoke near the ground through Sun 7 AM.

FriSatSun

Precipitation

What has fallen at Waterloo

0.11 in in the last 24 hours, 1.10 in over the last 3 days, to Fri 12 PM. Measured by radar and rain gauges, as water.

Last 24 hours
0.11in
Last 3 days
1.10in

Visibility

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

Visibility stays 9 miles or more through Sun 7 AM, lowest 9 miles Sat 4 AM.

FriSatSun

On the radar over Waterloo, IllinoisReflectivityStorm topsRain rateRain, last 24 hoursForecast temperatureForecast rain totalEvery picture

What is measuring near here

The 6 instruments nearest Waterloo, how far away each one is, how high it stands, and what kind of measurement it makes. The nearest is 0.2 miles away.

measured now4 instruments

measured daily2 instruments

WaterlooWTRI2

At a cooperative observer's station/0.2 mi away/702 ft/16 ft above here

snowfall, snow depth, precip, high, low

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Station report

The weather at Cahokia/St Louis, drawn

The nearest airport reporting now, 16.2 mi from Waterloo, Illinois. From its report of Oct 16, 2026, 12:53 PM local time: 3 of its 6 sheets.

The sky

Broken at 4,700 ft, overcast at 5,500 ft; the ceiling is 4,700 ft; visibility 10 mi or more.

Section of the sky over Cahokia/St Louis, height above the station to scale: broken cloud with its base at 4,700 feet, overcast cloud with its base at 5,500 feet, the ceiling at 4,700 feet, and visibility of 10 mi or more.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT CPSFIG. A THE SKY OVER CAHOKIA/ST LOUISSECTION, 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 STATION02,5005,0007,50010,000ETAGESLOWMIDDLETHE STATIONTHE CEILOMETER READS TO 12,000 FT, ABOVE THIS SHEETOVC 5,500 FTOVERCAST, 8 EIGHTHS OF THE SKYBKN 4,700 FTBROKEN, 5 TO 7 EIGHTHS OF THE SKYCEILING 4,700 FTVISIBILITY, MILES: 10 MI OR MORE0510TITLECahokia/St Louis, the skySTATION REPORT · ASOS CPSTYPESECTIONSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 1 of 6DATE2026-10-16IDSR-CPS-1DRAWN AS linework on paperSOURCES FB-SKY-001, FB-SKY-017, FB-SKY-016, FB-SKY-018

The air

56.0 F with a dew point of 39.0 F, 53 per cent relative humidity. Air lifted from the station would cool to its dew point, where cloud forms, about 3,900 ft up; the lowest cloud reported is at 4,700 ft.

Chart of the air at Cahokia/St Louis: temperature 56.0 degrees Fahrenheit and dew point 39.0, 53 per cent relative humidity; air lifted from the station cools along the dry rate and meets its dew point about 3,900 feet above the station, against the lowest cloud reported at 4,700 feet; height to scale.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT CPSFIG. B THE AIR AT CAHOKIA/ST LOUISTHE REPORTED TEMPERATURE AND DEW POINT, AND AIR LIFTED FROM THE STATION WITHOUT MIXING UNTIL IT SATURATES; HEIGHT ABOVE THE STATION TO SCALEFT ABOVE THE STATION01,0002,0003,0004,0005,0006,00020 F30 F40 F50 F60 F70 FSATURATES 3,900 FT ABOVE THE STATION, AT 35.3 FLOWEST CLOUD REPORTED, BKN 4,700 FTTEMPERATURE 56.0 FDEW POINT 39.0 FSPREAD 17.0 FRELATIVE HUMIDITY 53 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 POINTTITLECahokia/St Louis, the airSTATION REPORT · ASOS CPSTYPECHARTSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 2 of 6DATE2026-10-16IDSR-CPS-2DRAWN AS linework on paperSOURCES FB-WAT-002, FB-ENG-011, FB-ENG-005

The wind

From the northwest (310 degrees) at 16 mph, gusting 29 mph: force 4, a moderate breeze on the Beaufort scale. The strongest gust today was 39 mph.

Plan of the wind at Cahokia/St Louis, north up: blowing from 310 degrees, the northwest, at 16 miles an hour, gusting 29; beside it the Beaufort scale from calm to hurricane force, force 4, moderate breeze, marked.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT CPSFIG. C THE WIND AT CAHOKIA/ST LOUISPLAN, NORTH UP: THE WIND AS REPORTED, AND WHERE IT SITS ON THE BEAUFORT SCALENESWTHE STATIONFROM 310°BEAUFORT FORCELEAST WIND, MPH0CALM01LIGHT AIR12LIGHT BREEZE43GENTLE BREEZE84MODERATE BREEZE13NOW, 16 MPH5FRESH BREEZE196STRONG BREEZE25GUST, 29 MPH7NEAR GALE328GALE399STRONG GALE4710STORM5511VIOLENT STORM6412HURRICANE FORCE73TITLECahokia/St Louis, the windSTATION REPORT · ASOS CPSTYPEPLAN north upSCALENOT TO SCALEREVAS REPORTED SHEET 3 of 6DATE2026-10-16IDSR-CPS-3DRAWN AS linework on paperSOURCES FB-EVT-150, FB-ENG-008, FB-INS-002

The full report of Cahokia/St Louis, in 6 sheets, each beside the Field Book plates that explain it

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Snow on the ground

Elsewhere in Illinois

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

Near Waterloo

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

Near Waterloo

River and lake gauges