FORECAST CITY
Sign in
Shaded-relief map of West Caln, Pennsylvania: rivers, roads, the city limits and where the water drains.
PENNSYLVANIA · CHESTER COUNTY

West Caln

9,074 people, 700 ft above sea level in Chester County.

700 ftElevation, city center
9,074People, 2024 estimate
22 sq miLand area
Sunny 47°
Sunny now Dew point 29° · NW 14 mph · high 50°
City of West Caln River Interstate 2 miles
Explore the plate Order a print

The West Caln plate. Relief from Copernicus GLO-30; rivers and lakes from USGS NHD; watersheds from the USGS Watershed Boundary Dataset; roads and city limits from Census TIGER 2024.

MILE1
TODAY

Today in West Caln

NWS forecast and National Blend of Models · updated 3:00 PM EST
RIGHT NOW Wilmington Airport (KILG) · 2:51 PM
Sunny
47° Sunny Feels like 41° · high of 50° near 3 PM
WindNW 14 mphgusts 22
Humidity49%rising to 89% by morning
Pressure29.87 in →steady
Visibility10 mihaze-free
CloudsClear
UV index—no forecast
Dew point 29° · Dry37° by Tuesday: more humid
DryComfortableStickyMuggyOppressive
NEXT RAIN
Clear
Not this weeknone in the forecast for a week
LIKELY AMOUNT—nothing expected
LAST RAINNov. 120.06 in · 2 dry days
ALERTS & OUTLOOKS
No watches or warnings for Chester County
NWS Mount Holly and the Storm Prediction Center · checked 3:47 PM
SUN & MOON
↑ 6:47 AM4:48 PM ↓
10 h 0 m of daylight, 2 minutes less than yesterday
Waxing crescent, 25% lit. Next full moon: Nov. 24.
AIR & POLLEN
23
GOODAir quality index · ozone
No pollen source yet.

The next three days, hour by hour

Sky: clear, cloudy, night Rain likely National Blend of Models
SATURDAY, NOV. 14
SUNDAY, NOV. 15
MONDAY, NOV. 16
TUESDAY, NOV. 17
3p
6p
9p
Mid
3a
6a
9a
Noon
3p
6p
9p
Mid
3a
6a
9a
Noon
3p
6p
9p
Mid
3a
6a
9a
Noon
mostly cloudy day
partly cloudy night
partly cloudy night
partly cloudy night
mostly clear night
mostly sunny
mostly sunny
partly cloudy day
partly cloudy day
partly cloudy night
mostly clear night
mostly clear night
mostly clear night
clear day
mostly sunny
mostly sunny
mostly sunny
clear night
clear night
clear night
mostly clear night
mostly sunny
mostly sunny
clear day
TEMPERATURE °F
50°
36°
53°
34°
55°
33°
CHANCE OF RAIN
50%
WIND, MPH
13
10
10
9
10
10
13
13
12
9
8
7
8
8
12
10
8
7
5
5
6
6
7
8
HOW IT FEELS · DEW POINT
Dry: dew points 28 to 37°

The next seven days, and how sure we are

Forecast, with the range 8 in 10 ensemble members agree on Normal, about 56° / 38°
SAT Nov. 14 Mostly cloudy Mostly cloudy
50° 33°
0% rain — NW 13 A
SUN Nov. 15 Partly cloudy Partly cloudy
53° 31°
0% rain — NNW 13 A
MON Nov. 16 Mostly sunny Mostly sunny
56° 31°
0% rain — NNW 10 B
TUE Nov. 17 Sunny Sunny
58° 32°
0% rain — WNW 6 A
WED Nov. 18 Partly cloudy Partly cloudy
62° 32°
0% rain — W 5 A
THU Nov. 19 Mostly sunny Mostly sunny
64° 35°
0% rain — SW 5 A
FRI Nov. 20 Mostly sunny Mostly sunny
65° 38°
0% rain — NW 5 B
How sure are we? AModels agree: highs within 4° BSome spread: within 8° CWide spread: check back
Range from the National Blend of Models percentiles · graded on Forecast Scores
AIR MAIL

Where today’s air came from

The air arriving over West Caln about 5,000 feet above the ground was over British Columbia three days ago, and over Ontario a day ago, about 2,700 miles back along its path. It came down from about 14,600 feet up, warming and drying as it sank. Near the ground the air came from British Columbia; at 10,000 feet, from the open Pacific. It has stayed over land, which is why it feels dry. Traced back 72 hours through NOAA’s hourly RAP analyses and the GFS beyond them, nine paths at each of three heights.

THIS WEEK, NINE YEARS AGO Nov. 11, 2017

The coldest this week has been

16° on Nov. 11, 2017, the coldest reading for this week of the year since 1992. Next is 19° in 1996.

19°
16°
19962017
Source: NOAA RCC-ACIS, the New Holland 2 SE record since 1992.
MILE2
THE GROUND

What West Caln stands on

West Caln’s center stands about 700 ft above sea level. Within three miles the land runs from 480 ft to 970 ft, a difference of 490 ft: hilly country. The highest named summit within 15 miles is Welsh Mountain, about 1,080 ft, 7 miles north-northwest.

Under the town center the state geologic map shows Banded mafic gneiss, from the Precambrian.

The section below crosses 13 rock units mapped at the surface.

Terre Hill to Unionville, cut in half

A section northwest to southeast, 24 miles through the town center
250 ft500 ft750 ft1,000 ft WEST CALN700 ftCoatesville310 ftEast Fallowfield280 ftWest Branch Brandywine Creekabout 270 ft ← NW · Terre HillUnionville · SE →

Heights every 0.1 mile from the Copernicus GLO-90 surface model; vertical exaggeration about 25×. The colored band under the surface is the rock the state geologic map shows at the surface, not a picture of what lies beneath.

Rock at the surface along the line

Banded mafic gneiss

Gneiss. Age: Precambrian. About 6 mi of the line.

Peters Creek Schist

Mica-schist, quartzite. Age: Paleozoic, 252 to 542 million years old. About 3 mi of the line.

Chickies Formation

Quartzite, schist. Age: Cambrian, 487 to 542 million years old. About 3 mi of the line.

"Glenarm Wissahickon" formation

Mica-schist. Age: Paleozoic, 252 to 542 million years old. About 3 mi of the line.

Ledger Formation

Dolostone. Age: Cambrian, 487 to 542 million years old. About 2 mi of the line.

Felsic and intermediate gneiss

Muscovite-gneiss. Age: Precambrian. About 2 mi of the line.

From the USGS State Geologic Map Compilation (Horton and others, 2017), the states’ geologic maps joined at a common scale. 7 smaller units along the line are not listed.

Heights from Copernicus GLO-90 (a surface model: it includes buildings and tree canopy); summits from USGS GNIS; rivers from USGS NHDPlus HR; rock from the USGS State Geologic Map Compilation.

MILE3
THE WATER

Where West Caln’s rain goes

A raindrop that lands in West Caln reaches Delaware Bay and the Atlantic Ocean by way of Birch Run, West Branch Brandywine Creek, Brandywine Creek, the Christina and the Delaware: about 85 river miles.

THE WAY DOWN, TO SCALE
West Caln≈ 85 mi · Delaware Bay and the Atlantic Ocean
FROM THE CENTER OF WEST CALN ≈ 85 mi to Delaware Bay and the Atlantic Ocean Birch Run → West Branch Brandywine Creek → Brandywine Creek → Christina → Delaware

Traced down the USGS NHDPlus V2.1 river network from the Census center point of West Caln; river miles along the main stem, rounded.

MILE5
THE ALMANAC

West Caln’s year

1991–2020 normals · records since 1992 · New Holland 2 SE, 11 mi west-northwest

West Caln has a hot-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 24° in January. A normal year brings about 34 inches of snow; with the rain, that comes to about 47 inches of water.

39°24°42°25°51°32°63°42°73°53°81°62°86°66°84°65°77°58°65°47°54°36°43°29° JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC 12 TODAY WEST CALN 46.8 in rain and snowmelt
Normal high to low, by month Record high to low, by day Rain by month Freezing
July, average86° / 66°high / low, the warmest month
January, average39° / 24°high / low, the coldest month
Rain and melted snow46.8 inwettest months: September and October
Snow a year33.5 insnowiest: February
Hottest on record105°FJuly 2, 2026
Coldest on record−13°FJanuary 19, 1994
Wettest day on record6.74 inOctober 9, 2005
Snowiest day on record26.0 inJanuary 23, 2016
90° days a year20very few reach 100°
Nights at or below 32°97and 19 days that stay below freezing
Climate typeHot-summer humid continentalKöppen Dfa

AROUND THE RING

1Freeze seasonfrom the first fall freeze, about Oct. 31, to the last in spring, about April 13 (median dates)
2Lows below freezingNov. 29 to March 18; normal lows fall below 32°
NOVEMBER 14 IN THE RECORD

On November 14 West Caln normally reaches 54° and falls to 37°. The record high is 70°, in 1993; the record low 25°, in 2004. The most rain on this date, 0.50 in, fell in 2008.

MONTH BY MONTH
JanFebMarAprMayJunJulAugSepOctNovDec
Normal high39°42°51°63°73°81°86°84°77°65°54°43°
Normal low24°25°32°42°53°62°66°65°58°47°36°29°
Rain and melt, in3.342.784.113.563.524.504.434.274.904.563.183.69
Snow, inches10.310.65.51.20.00.00.00.00.00.31.04.6
Record high70° (2007)80° (2018)87° (1998)93° (2002)95° (2026)98° (2025)105° (2026)101° (2001)96° (2023)93° (2019)82° (2024)75° (1998)
Record low−13° (1994)−2° (2015)2° (2015)20° (2021)28° (2020)40° (2020)50° (2021)44° (2024)34° (2020)27° (1992)13° (2018)2° (2017)

Normals 1991–2020 and records since 1992 at New Holland 2 SE, 11 miles west-northwest. NOAA, through RCC-ACIS.

MILE7
ON THE NETWORK

Around West Caln on the Forecast Network

Neighboring plates

Reading PA · 22 MI 22 miles north Philadelphia PA · 40 MI 40 miles east Baltimore MD · 63 MI 63 miles southwest Washington DC · 98 MI 98 miles southwest New York NY · 112 MI 112 miles northeast Hempstead NY · 127 MI 127 miles east
FORECASTCITY
Map of West Caln, Pennsylvania. Explore the plate
PENNSYLVANIA · CHESTER

West Caln

9,074 people, 700 ft above sea level in Chester County.

700 ftElevation
9,074People
22 sq miLand
Sunny 47°
SunnyDew point 29°
1

Today in West Caln

NEXT 15 HOURS
Now mostly cloudy day 50° 0%
6p mostly cloudy night 47° 1%
9p partly cloudy night 41° 1%
12a partly cloudy night 39° 1%
3a mostly clear night 37° 1%
6a mostly clear night 36° 0%
Clear
NEXT RAINNone this week
→
Sat0%
Mostly cloudy Mostly cloudy
33
50
A
Sun0%
Partly cloudy Partly cloudy
31
53
A
Mon0%
Mostly sunny Mostly sunny
31
56
B
Tue0%
Sunny Sunny
32
58
A
Wed0%
Partly cloudy Partly cloudy
32
62
A
Thu0%
Mostly sunny Mostly sunny
35
64
A
Fri0%
Mostly sunny Mostly sunny
38
65
B
Letters show how sure the forecast is: A, models agree; B, some spread; C, check back. Sample data.
THIS WEEK, NINE YEARS AGO · NOV. 11, 2017

16°, the coldest this week of the year has been since 1992.

2

What West Caln stands on

West Caln’s center stands about 700 ft above sea level. Within three miles the land runs from 480 ft to 970 ft, a difference of 490 ft: hilly country. The highest named summit within 15 miles is Welsh Mountain, about 1,080 ft, 7 miles north-northwest.

West Caln, northwest to southeast West Caln700 ft ← NWSE → 24 miles through the town center; vertical exaggeration about 48×. Colors: rock at the surface.
Elevation, center700 ft
Within 3 miles480 to 970 ft
Lie of the landHilly (490 ft of relief)
High point nearbyWelsh Mountain, 1,080 ft, 7 mi north-northwest
Rock at the surfaceBanded mafic gneiss
Its agePrecambrian
5

West Caln’s year

West Caln has a hot-summer humid continental climate. Summer afternoons average 86° in July; winter nights fall to about 24° in January. A normal year brings about 34 inches of snow; with the rain, that comes to about 47 inches of water.

JANFEBMARAPRMAYJUNJULAUGSEPOCTNOVDEC 12 46.8 in
July, average86° / 66° · high / low, the warmest month
January, average39° / 24° · high / low, the coldest month
Rain and melted snow46.8 in · wettest months: September and October
Snow a year33.5 in · snowiest: February
Hottest on record105°F · July 2, 2026
Coldest on record−13°F · January 19, 1994
Wettest day on record6.74 in · October 9, 2005
Snowiest day on record26.0 in · January 23, 2016
90° days a year20 · very few reach 100°
Nights at or below 32°97 · and 19 days that stay below freezing
Climate typeHot-summer humid continental · Köppen Dfa
1Freeze season · from the first fall freeze, about Oct. 31, to the last in spring, about April 13 (median dates)
2Lows below freezing · Nov. 29 to March 18; normal lows fall below 32°
NOVEMBER 14 IN THE RECORD

On November 14 West Caln normally reaches 54° and falls to 37°. The record high is 70°, in 1993; the record low 25°, in 2004. The most rain on this date, 0.50 in, fell in 2008.

Normals 1991–2020 and records since 1992 at New Holland 2 SE, 11 miles west-northwest. NOAA, through RCC-ACIS.
3

Where the rain goes

≈ 85 mito the AtlanticBirch Run → West Branch Brandywine Creek → Brandywine Creek → Christina → Delaware

A raindrop that lands in West Caln reaches Delaware Bay and the Atlantic Ocean by way of Birch Run, West Branch Brandywine Creek, Brandywine Creek, the Christina and the Delaware: about 85 river miles.