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Derby, Connecticut

City in New Haven County, Connecticut

Air quality

The air at Derby

Index 17, good, led by fine particles. Read at 11 PM from its reporting area, New Haven (CT), 8 miles off.

17Good
  • Fine particles (PM2.5)17Good9.3 mi
  • Ozone16Good29 ppb9.3 mi
  • Coarse particles (PM10)7Good9.3 mi
  • Nitrogen dioxide7Good7.7 ppb9.3 mi
  • Sulfur dioxide0Good0.3 ppb9.3 mi
  • Carbon monoxide-0.2 ppm9.3 mi

The days ahead

Good each day through Today, led by fine particles. Yesterday measured 53, moderate.

Smoke, the next 45 hours

No smoke near the ground through Sat 8 PM.

FriSat

Precipitation

What has fallen at Derby

None in the last 3 days, to Thu 11 PM. Measured by radar and rain gauges, as water.

Last 24 hours
0.00in
Last 3 days
0.00in

Visibility

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

Mist or haze: visibility falls to 1 miles Fri 8 PM.

FriSat

On the radar over Derby, ConnecticutReflectivityStorm topsRain rateRain, last 24 hoursForecast temperatureForecast rain totalEvery picture

What is measuring near here

The 6 instruments nearest Derby, 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 now4 instruments

New HavenNDBC-NWHC3

At a river or reservoir gauge/9.2 mi away/-/- ft from here

temp, wind, gust, humidity, pressure

Rank333of 375

measured daily2 instruments

Derby 1.0 SSECT-NH-102

In a volunteer observer's own ground/0.6 mi away/109 ft/159 ft below here

precip, snowfall, snow depth

Rank204of 375

AnsoniaANSC3

At a cooperative observer's station/1.9 mi away/177 ft/91 ft below here

snowfall, snow depth, precip, high, low

Rank-

Station report

The weather at New Haven/Tweed, drawn

The nearest airport reporting now, 10.7 mi from Derby, Connecticut. From its report of Oct 15, 2026, 11:53 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 New Haven/Tweed, 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 HVNFIG. A THE SKY OVER NEW HAVEN/TWEEDSECTION, 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 MORE0510TITLENew Haven/Tweed, the skySTATION REPORT · ASOS HVNTYPESECTIONSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 1 of 6DATE2026-10-16IDSR-HVN-1DRAWN AS linework on paperSOURCES FB-SKY-001

The air

58.0 F with a dew point of 48.0 F, 69 per cent relative humidity. Air lifted from the station would cool to its dew point, where cloud forms, about 2,300 ft up.

Chart of the air at New Haven/Tweed: temperature 58.0 degrees Fahrenheit and dew point 48.0, 69 per cent relative humidity; air lifted from the station cools along the dry rate and meets its dew point about 2,300 feet above the station; height to scale.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT HVNFIG. B THE AIR AT NEW HAVEN/TWEEDTHE REPORTED TEMPERATURE AND DEW POINT, AND AIR LIFTED FROM THE STATION WITHOUT MIXING UNTIL IT SATURATES; HEIGHT ABOVE THE STATION TO SCALEFT ABOVE THE STATION01,0002,0003,00030 F40 F50 F60 F70 FSATURATES 2,300 FT ABOVE THE STATION, AT 45.8 FTEMPERATURE 58.0 FDEW POINT 48.0 FSPREAD 10.0 FRELATIVE HUMIDITY 69 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 POINTTITLENew Haven/Tweed, the airSTATION REPORT · ASOS HVNTYPECHARTSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 2 of 6DATE2026-10-16IDSR-HVN-2DRAWN AS linework on paperSOURCES FB-WAT-002, FB-ENG-011, FB-ENG-005

The wind

From the south (180 degrees) at 12 mph: force 3, a gentle breeze on the Beaufort scale. The strongest gust today was 22 mph.

Plan of the wind at New Haven/Tweed, north up: blowing from 180 degrees, the south, 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 HVNFIG. C THE WIND AT NEW HAVEN/TWEEDPLAN, NORTH UP: THE WIND AS REPORTED, AND WHERE IT SITS ON THE BEAUFORT SCALENESWTHE STATIONFROM 180°BEAUFORT FORCELEAST WIND, MPH0CALM01LIGHT AIR12LIGHT BREEZE43GENTLE BREEZE8NOW, 12 MPH4MODERATE BREEZE135FRESH BREEZE196STRONG BREEZE257NEAR GALE328GALE399STRONG GALE4710STORM5511VIOLENT STORM6412HURRICANE FORCE73TITLENew Haven/Tweed, the windSTATION REPORT · ASOS HVNTYPEPLAN north upSCALENOT TO SCALEREVAS REPORTED SHEET 3 of 6DATE2026-10-16IDSR-HVN-3DRAWN AS linework on paperSOURCES FB-EVT-150, FB-ENG-008, FB-INS-002

The full report of New Haven/Tweed, in 6 sheets, each beside the Field Book plates that explain it

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Snow on the ground

Elsewhere in Connecticut

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

Near Derby

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

Near Derby

River and lake gauges