Storm Station
Walnut, California
75° 85°/67°
Overcast· Feels like 75°·Light air 4 mph NNW
Mostly cloudy, with a low around 68. Southeast wind around 5 mph.
0UV Low
75Air quality
72%Humidity
100%Cloud
Now
12:30 AM
75feels75
now, overcast
Today
Sep 27
8567
UV 7
overcast
Mon
Sep 28
8459
UV 7
mostly clear day
Tue
Sep 29
8669
UV 7
clear day
Wed
Sep 30
8770
UV 7
clear day
Thu
Oct 1
9372
UV 7
clear day
Fri
Oct 2
10279
UV 7
clear day
Sat
Oct 3
10285
UV 7
clear day
75°
85°67°
84°59°
86°69°
87°70°
93°72°
102°79°
102°85°

As of 12:30 AM in Walnut, California.

What is measuring near here

The 4 instruments nearest Walnut, 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 now2 instruments

Tonner CanyonTNRC1

At a river or reservoir gauge/5.9 mi away/1,335 ft/737 ft above here

temp, wind, gust, humidity, pressure

Rank631of 3,115

La Verne/BrackettPOC

At an airfield/6.6 mi away/1,010 ft/412 ft above here

temp, wind, gust, visibility, precip, pressure

Rank3,086of 3,115

measured daily2 instruments

Walnut 0.5 SSWCA-LA-120

In a volunteer observer's own ground/0.3 mi away/565 ft/33 ft below here

precip, snowfall, snow depth

Rank-

Covina YardCTFC1

At a cooperative observer's station/4.7 mi away/594 ft/4 ft below here

snowfall, snow depth, precip, high, low

Rank-

Station report

The weather at Tonner Canyon, drawn

The nearest instrument reporting now, 5.9 mi from Walnut. From its report of Sep 26, 2026, 11:57 PM local time: 3 of its 5 sheets.

The air

74.0 F with a dew point of 55.8 F, 53 per cent relative humidity. Air lifted from the station would cool to its dew point, where cloud forms, about 4,200 ft up.

Chart of the air at Tonner Canyon: temperature 74.0 degrees Fahrenheit and dew point 55.8, 53 per cent relative humidity; air lifted from the station cools along the dry rate and meets its dew point about 4,200 feet above the station; height to scale.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT TNRC1FIG. B THE AIR AT TONNER CANYONTHE REPORTED TEMPERATURE AND DEW POINT, AND AIR LIFTED FROM THE STATION WITHOUT MIXING UNTIL IT SATURATES; HEIGHT ABOVE THE STATION TO SCALEFT ABOVE THE STATION01,0002,0003,0004,0005,0006,00040 F50 F60 F70 F80 FSATURATES 4,200 FT ABOVE THE STATION, AT 51.6 FTEMPERATURE 74.0 FDEW POINT 55.8 FSPREAD 18.2 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 POINTTITLETonner Canyon, the airSTATION REPORT · DCP TNRC1TYPECHARTSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 1 of 5DATE2026-09-27IDSR-TNRC1-1DRAWN AS linework on paperSOURCES FB-WAT-002, FB-ENG-011, FB-ENG-005

The wind

From the south (175 degrees) at 6 mph, gusting 8 mph: force 2, a light breeze on the Beaufort scale. The strongest gust today was 21 mph.

Plan of the wind at Tonner Canyon, north up: blowing from 175 degrees, the south, at 6 miles an hour, gusting 8; beside it the Beaufort scale from calm to hurricane force, force 2, light breeze, marked.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT TNRC1FIG. C THE WIND AT TONNER CANYONPLAN, NORTH UP: THE WIND AS REPORTED, AND WHERE IT SITS ON THE BEAUFORT SCALENESWTHE STATIONFROM 175°BEAUFORT FORCELEAST WIND, MPH0CALM01LIGHT AIR12LIGHT BREEZE4NOW, 6 MPH3GENTLE BREEZE8GUST, 8 MPH4MODERATE BREEZE135FRESH BREEZE196STRONG BREEZE257NEAR GALE328GALE399STRONG GALE4710STORM5511VIOLENT STORM6412HURRICANE FORCE73TITLETonner Canyon, the windSTATION REPORT · DCP TNRC1TYPEPLAN north upSCALENOT TO SCALEREVAS REPORTED SHEET 2 of 5DATE2026-09-27IDSR-TNRC1-2DRAWN AS linework on paperSOURCES FB-EVT-150, FB-ENG-008

The column

At 1,335 ft above sea level, 5 per cent of the atmosphere's air lies below the station. The standard atmosphere puts the pressure there at 28.51 inHg and the temperature at 54.2 F; it reports 74.0 F, 19.8 F warmer than standard.

Section from sea level of where Tonner Canyon stands in the atmosphere, height to scale: the station 1,335 feet above sea level with 5 per cent of the air below it; the standard atmosphere's pressure there, 28.51 inches of mercury, and temperature, 54.2 degrees Fahrenheit.1122334455667788AABBCCDDEE© 2026 STORM STATION 247THE FIELD BOOKSTATION REPORT TNRC1FIG. D WHERE TONNER CANYON STANDS IN THE ATMOSPHERESECTION FROM SEA LEVEL, HEIGHT TO SCALE, THE STATION IN THE STANDARD ATMOSPHEREFT ABOVE SEA LEVEL05,00010,00015,000SEA LEVEL, 29.92 inHg IN THE STANDARD ATMOSPHERETONNER CANYON5 PER CENT OF THE AIR BELOW IT1,335 FT10 PER CENT OF THE AIR BELOW, 2,890 FT20 PER CENT OF THE AIR BELOW, 6,050 FT30 PER CENT OF THE AIR BELOW, 9,540 FT40 PER CENT OF THE AIR BELOW, 13,470 FTSTANDARD PRESSURE HERE28.51 inHgSTANDARD TEMPERATURE HERE54.2 FTEMPERATURE, REPORTED74.0 FTITLETonner Canyon, the columnSTATION REPORT · DCP TNRC1TYPESECTIONSCALEHEIGHT TO SCALEREVAS REPORTED SHEET 3 of 5DATE2026-09-27IDSR-TNRC1-3DRAWN AS linework on paperSOURCES FB-ENG-001, FB-ENG-003

The full report of Tonner Canyon, in 5 sheets, each beside the Field Book plates that explain it

-in

Snow on the ground

Elsewhere in California

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

Near Walnut

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